


NASA’s Lost and Forgotten Space Missions

by MrToddWilkins (orphan_account)



Series: Space stuff [6]
Category: NASA - Fandom
Genre: Fanwork Research & Reference Guides
Language: English
Status: Completed
Published: 2019-09-07
Updated: 2019-10-28
Packaged: 2020-10-12 03:35:00
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 44
Words: 35,871
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20557553
Author URL: https://archiveofourown.org/users/orphan_account/pseuds/MrToddWilkins
Summary: Plans for what could have been in space.





	1. 1952:the Collier’s space exploration articles

Probably the most distinctive feature of the _Collier's_ magazine space articles is the magnificently quaint artwork of Chesley Bonestell, Fred Freeman, and Rolf Klep. The _Collier's_ moon articles were preceded by an article ("Man Will Conquer Space Soon," March 22, 1952) describing how reusable rockets resembling Second World War V-2 missiles would haul into orbit parts for a spinning donut-shaped space station 250 feet across with a crew of 80. The $4 billion station is an Earth observations post, an observatory for mapping the moon and planets, and a staging area for moon missions. The first lunar expedition, set to land in 1975, does nothing by half measures. It includes 50 astronaut explorers,a six-week surface stay in Sinus Roris (the Man in the Moon's left eyebrow),three large landers (two containing 20 crew each and one for cargo and 10 crew,three pressurized caterpillar-tracked rovers capable of supporting seven astronauts for 12 hours at a stretch. Each sports a crane capable of lifting another rover and can tow up to three trailers,a 500-mile, 10-day traverse by 10 astronauts from the landing site to the 24-mile-wide crater Harpalus and back,and eventually a surface outpost consisting of two pre-fabricated quonset huts tucked away inside a lunar crevasse for protection from meteoroids and solar and cosmic radiation.

Moonship assembly commences six months before planned departure. Each day two cargo shuttles deliver a total of 70 tons of components, fuel, and supplies to orbit near the space station. When complete, each lander weighs 4370 tons, and measures 160 feet tall ("nine feet more than. . .the Statue of Liberty") and 110 feet wide. Fabric tanks hold hydrazine fuel, nitric acid oxidizer, hydrogen peroxide turbopump fuel, and helium pressurant for the 30 rocket engines. At the top of the spacecraft is the inflatable fabric personnel sphere, 33 feet in diameter, with five decks. From top to bottom, they are

  * _Deck 1 _contains the Bridge, where the captain, pilot, engineer, and radio operator man control consoles (Fred Freeman's cutaway painting shows Von Braun in the captain's seat). The Bridge has several windows and glass domes through which point navigational apparatus. 

  * _Deck 2_ contains the moonship's bulky automation system, into which the navigator and his two assistants feed control tapes from an extensive library covering every eventuality. 

  * _Deck 3_, the largest deck, contains living quarters with bunks and a semi-automated cafeteria. 

  * _Deck 4_ contains storage and the ship's toilet. 

  * _Deck 5_ contains engineering, a cramped compartment containing life support equipment and batteries charged by a solar dynamic power system mounted outside the sphere. A hatch in deck 5's floor leads into a cylindrical airlock which opens onto a catwalk 130 feet above the lunar surface. 

In the event of problems with one or more spacecraft, the two crew landers can each return the entire expedition complement to the Earth-orbiting space station. The one-way cargo ship resembles the crew landers, but has a cylindrical, metal-walled cargo compartment in place of tanks holding propellant for return to the space station. The 75-foot-long cargo compartment holds 285 tons of supplies. As soon as the ships land, cranes lower the explorers and tractors to the surface. The explorers locate a crevasse and unload the cargo lander. They then remove the cargo compartment, split it lengthwise down the middle to form two quonset huts, and lower it into the crevasse. The huts house barracks, a workshop, a darkroom, and rock analysis laboratories. Despite its ambitious complexity, the expedition's price tag is only $300 million.


	2. 1953:The Mars Project

From 1945 to 1950, Wernher von Braun was interned at White Sands Proving Ground in New Mexico with about 60 other German rocket scientists spirited out of Germany by the U.S. Army. In 1947-48, to relieve boredom, Von Braun wrote a novel about an expedition to Mars. In the words of Frederick Ordway and Mitchell Sharpe, writing in their history _The Rocket Team_, the novel "proved beyond doubt that its author was an imaginative scientist but an execrable manufacturer of plot and dialog." (p. 408) In 1950, the novel's appendix - a collection of mathematical proofs supporting its spacecraft designs and mission plan - was published in West Germany as _Das Marsprojekt_. The University of Illinois Press published this English-language edition 3 years later. Von Braun describes a Mars expedition "on a grand scale," with ten 4000-ton ships and 70 crewmen. Seven vessels are true spaceships without streamlining designed for the round-trip Mars voyage. They resemble the passenger moonships described in the October 1952 _Collier's_ articles.

Three one-way ships have winged landing gliders in place of inflatable personnel spheres.

  * _The spacecraft are assembled in Earth orbit_ from parts launched by 3-stage ferry rockets. Nine hundred and fifty ferry flights are required to assemble the Mars "flotilla" in Earth orbit. Von Braun estimates that each ferry rocket needs 5583 tons of propellants to place about 40 tons of cargo into orbit, so 5,320,000 tons will be needed to launch all the Mars flotilla parts. Von Braun points out that "about 10 per cent of an equivalent quantity of high octane aviation gasoline was burned during the six months' operation of the Berlin Airlift." Total propellant cost is $500 million. 

  * _Earth-to-Mars coast_ lasts 8 months. 

  * _Mars orbit insertion and the first glider lands_ \- One landing glider separates, deorbits, and glides to a landing on skids on one of the polar ice caps. Von Braun chooses the polar caps because he believes that they are the only places on the planet where the crew can be reasonably certain of a smooth landing site. 

  * _Overland traverse_ \- The first men on Mars abandon their glider on the icecap and conduct a heroic 4000-mile overland trek to Mars' equator, where they build a landing strip for the landing wheels of the two gliders waiting in orbit. 

  * _Wheeled gliders land_ \- As soon as their wheels stop, the explorers unbolt the gliders' delta wings and hoist the bullet-shaped fuselages upright so that they stand on their tails, ready for rapid return to orbit in case of emergency. They then set up an inflatable habitat, their base of operations for a 400-day survey of Mars' canals and deserts. 

  * _Ascent to Mars orbit_ and rendezvous with the seven remaining Mars ships so that their crews can transfer (no docking is assumed). 

  * _Return to Earth_ \- The journey back to Earth orbit lasts 8 months.


	3. 1954:where to land on the Moon?

Dr. Wilkins, a Fellow of the Royal Astronomical Society, proposes that lunar expeditions land on any of the dark, flooded "craterform features or walled plains." These are, he writes, level and smooth enough for a safe landing, but surrounded by interesting places to explore. He rejects the _maria_as landing sites, writing that they "are too open to be considered as really suitable sites. Why land on a congealed lava flow miles from any object of interest?" Wilkins suggests instead Stofler, Schomberger, Pontecoulant, and Schickard craters in the south; Sinus Medii (later an Apollo alternate site), Ptolemy, Grimaldi, Billy, and Vendelinus in the equatorial latitudes; and, in the north, Plato, Endymion, Anaximander, Meton, Archimedes, Otto Struve, Euler, and Condorcet. He adds that Earth-based observations of the lunar surface will probably never be sufficient to fully characterize a landing site, so crews will need to be able to make the final site selection when they arrive.


	4. 1956:The Exploration of Mars

The first four chapters of this classic book cover the history of Mars observation and the current state of knowledge ("this is the picture of Mars at mid-century: A small planet of which three-quarters is cold desert, with the rest covered with a sort of plant life that our biological knowledge cannot encompass. . ."). The authors concede that "it is entirely possible. . . that within a decade or so successful tests with some sort of nuclear rocket propulsion system might be accomplished. . .", but for the present, "it is exciting and instructive" to show that a Mars expedition can be carried out using 1950s technology. Their Mars expedition is a cut-price version of the 1953 _The Mars Project_/1954 _Collier's_ expedition, with just 12 crew in two ships. A single passenger ship completes the round-trip voyage. The craft, which resembles the passenger moonships in the 1952 _Collier's moon_ articles,has an inflatable personnel sphere 26 feet across, with a control room on deck 1 and living quarters on decks 2 and 3. The one-way cargo ship carries the expedition's 177-ton landing glider in place of a personnel sphere. Both ships weigh 1870 tons before departing Earth orbit; the passenger ship weighs only 38.4 tons when it returns to Earth orbit. A total of 400 unmanned cargo rocket and manned shuttle flights are needed to assemble the expedition. Mars ship assembly flights occur at the rate of two per day over seven months. Upon reaching Mars, the crew turns powerful telescopes on proposed landing sites selected using telescopes on the Earth-orbiting space station. Equatorial sites are preferred because they are warmest. Margaritifer Sinus is the prime candidate because there are many different kinds of surface features nearby, including two canals. Nine of the 12 crew descend to Mars' surface in the glider, leaving three in orbit to mind the passenger ship's systems. The glider lands on skids at a maximum speed of 120 miles per hour. After the glider comes to rest, the intrepid explorers walk out onto the wing, leap 18 feet to the ground (the equivalent of a 6-foot drop in Earth gravity), and immediately prepare the ship for an emergency liftoff - this despite having just spent 8 months in weightlessness. They remove the wings and hoist the fuselage upright so it stands on its tail using the expedition's two caterpillar tractors. Then they inflate a 20-foot hemispherical pressurized "tent" to serve as expedition headquarters. After a year of exploring the surface, they lift off, rendezvous with the passenger ship to rejoin their compatriots in orbit, and blast for Earth. The last drops of fuel place the ship in a 56,000-mile Earth orbit. A relief ship ascends from the space station to collect the crew,who abandon the Mars ship in high orbit as a monument to the early days of planetary exploration.


	5. 1956:Crocco’s Earth-Mars-Venus expedition

Crocco notes that a minimum-propellant transfer from Earth to Mars orbit requires (according to Arthur Clarke) 259 days, after which the spacecraft must remain at Mars for 425 days waiting for Mars and Earth to line up for a 259-day trip back to Earth. This yields a total voyage duration of nearly 3 years. Through a series of charts and formulae Crocco demonstrates that a spacecraft could, in theory, travel from Earth to Mars, perform a reconnaissance Mars flyby (that is, not stop over in Mars orbit), and return to Earth with a total trip time of about one year. The spacecraft would fire its rocket only to leave Earth - it would coast for the remainder of the flight. The Mars flyby mission requires less than half as much energy - therefore, propellant - as the Mars stopover flight. The flyby spacecraft would have "a telescope of moderate aperture. . .[with] a magnifying power. . .such as to reveal and distinguish natural accidentalities of the planet from artificial construction. . ." Crocco states that, in practice, Mars' gravity will deflect the flyby spacecraft's course so it misses Earth on the return leg unless it remains more than 400 martian radii (about 800,000 miles) from Mars' surface. Passing so far from Mars would, of course, "frustrate the exploration scope of the trip." He proposes sending the flyby craft past Venus on the return leg so that that planet's gravity can bend the craft's course toward Earth without reliance on propellant. One such Earth-Mars-Venus-Earth voyage requires 113 days for the Earth-Mars leg, 154 days for the Mars-Venus leg, and 98 days for the Venus-Earth leg. The Venus flyby is an exploration bonus, Crocco states, allowing the crew to glimpse, perhaps, "the riddle which is concealed by her thick atmosphere." An opportunity to begin an Earth-Mars-Venus-Earth flight will occur in June 1971, Crocco calculates.


	6. 1957:A Rocket around the Moon

In June 1957, launch of the U.S. Vanguard 1 satellite was thought imminent, leading the authors of this popular-audience article to write that

> [s]ometime in the coming months a silvery 20-pound sphere will be shot into the sky and will fly around the earth at a distance of 300 miles or more. . .Once man has successfully launched this artificial satellite, the next interesting target in space, of course, will be the moon. How soon will we reach the moon? With luck and sufficient effort, we ought to be able to do it within five years.

The authors propose an automated moon probe dubbed "Cow", weighing between 400 and 800 pounds. A 100-foot-tall, 120-ton rocket boosts Cow to a speed of 23,827 miles per hour on a path directed toward the moon. If the moon and Sun lacked gravity, Cow would enter an elliptical orbit taking it 280,000 miles from Earth - that is, about 40,000 miles beyond the moon. The gravitational attraction of the moon and Sun means, however, that Cow follows a "distorted" path to a point 1281 miles from the moon 75.6 hours after launch. The probe then swings around the moon, collecting data all the while, and falls back to Earth, striking the atmosphere at 25,000 miles per hour 157 hours after launch. Though atmospheric friction will drive Cow's temperature to 5000 degrees centigrade, Ehricke and Gamow maintain that "preventing the capsule from burning up by means of insulation and a cooling system is not technically prohibitive." They then propose a follow-on sample-collection mission using two probes on a Cow-type trajectory. The lead probe would drop an atomic bomb on the moon, blasting a debris cloud far into space; then the trailing probe, through "a miracle of electronic guidance," would "dive into the cloud, collect some of the spray and emerge from its dive by means of an auxiliary jet."


	7. 1957:Around the Moon in 80 Hours

In 1955 the Soviet Union declared that it would place a satellite into Earth orbit during the 18-month International Geophysical Year (1957-58). Few in the West took this claim seriously, however, until the Soviets test-launched the world's first intercontinental missile, the R-7, on August 21, 1957. The Soviets then used the R-7 to launch the first and second satellites, 83.6-kilogram Sputnik 1 (October 4, 1957) and 508-kilogram Sputnik 2 (November 3, 1957). The amount of weight the R-7 could place in orbit startled U.S. rocketeers. The first successful U.S. satellite, Explorer 1 (launched January 31, 1958), weighed just 14 kilograms; the third Soviet satellite, Sputnik 3 (launched May 15, 1958), weighed nearly 100 times as much (1330 kilograms). Even as the U.S. launched its first satellite, two new heats in the space race commenced - the race to hit the moon with an unmanned probe, and the race to launch a man into orbit. At the time this paper was presented, neither race yet had a victor. The present paper proposes in effect to combine these two races by launching a man around the moon. The authors, with Martin Company in Denver, Colorado, warn that the "Russians may have such a lead. . .that they will have made landings on the moon before. . .our first circumlunar flight," and project that the Soviet Union will be capable of a manned circumlunar flight in 1963, a feat the U.S. will not match until 1967. They add, however, that "on the technical side, at least, there seems to be no reason why this goal could not be accomplished by 1963." (Many in the U.S. at this time perceived that U.S. spaceflight was held back by lack of political will on the part of the Eisenhower Administration.) Their circumlunar flight contains the following features:

  * Prior to circumlunar flight, the pilot makes several weightless Earth-orbital flights. During these he learns, among other things, to empty his "urinary bladder on a fixed schedule, possibly using an alarm clock, since the voiding stimulus has been found to be a function of the weight of the bladder contents." 

  * Cole and Muir propose a four-stage launch vehicle. They estimate that a 160,000-pound-thrust missile can be expected by 1963; for the circumlunar flight they propose clustering four of these to create a first stage with 610,000 pounds of thrust. The second stage is one 160,000-pound thrust rocket, the third stage is a 40,000-pound-thrust rocket, and the fourth stage generates 10,000 pounds of thrust. 

  * Though a 2-week trip requires the least energy (thus a smaller launch vehicle), they opt for a three or four day trip, stating that "[f]or one man alone in a tiny sealed capsule on a journey of 250,000 miles from the earth, the difference between three or four days and two weeks might approach infinity." Reduced trip time also reduces the amount of supplies needed. The energy needed to reduce the trip time from 2 weeks to 4 days is modest, they estimate; reducing it still further requires much energy. 

  * The circumlunar capsule weighs 9000 pounds, of which 80 pounds is food, water, and oxygen, 3120 pounds is chemicals for generating electricity, and 500 pounds is a heatshield for high-speed Earth atmosphere reentry. 

  * The capsule's circumlunar path has three parts. The outbound leg lasts 35.35 hours, and is followed by a 9.3-hour hyperbola (curving flyby) near the moon. The capsule passes 10 miles over the moon's farside, where "[t]he synthesizing power of the human brain will permit collection of more accurate and more meaningful data than could be obtained by photographic techniques alone." The fall back to Earth lasts 35.35 hours. 

  * Before Earth atmosphere reentry the pilot's "bathtub-type" couch fills with water to shield him from reentry deceleration. Cole & Muir write that, because "the water would be needed only in the last phase of the trip, it could be reserve drinking or washing water."
  * After reentry, fins deploy for atmospheric steering. Landing is by parachute at sea or in the United States. The authors conclude by saying, "[t]ime may well prove that the man who climbs out of this capsule to receive the cheers of the recovery crew. . .made a voyage of greater importance to the human race than that of Columbus."


	8. 1959:Project Horizon

Probably the most famous - certainly the most notorious - lunar base study is Project Horizon, the U.S. Army plan to establish a lunar fort by 1967. Although not listed in the document, German rocket engineer H. H. Koelle - of the Army Ballistic Missile Agency (ABMA), under Wernher von Braun - was study leader. ABMA had been responsible for launching the first U.S. satelite, Explorer 1, on January 31, 1958, following the failed launch of the civilian Vanguard 1 satellite on December 6, 1957. In Koelle's report, reusable Saturn I and Saturn II rockets boost cargo to the moon beginning in January 1965. The three-stage Saturn I is used primarily for Earth-orbital operations. The report states that the four-stage Saturn II can boost about 13.4 tons to Earth escape velocity. Using the Saturn II and a direct lunar flight ending with a lunar soft-landing, only three tons of cargo can be put on the moon. To get around this limitation, Project Horizon proposes refueling the Saturn II third stage from a tank farm in low Earth orbit. This "indirect" transport method - which delivers all crew and 1/3 of the outpost's cargo - allows 70-ton moonships to deliver 24 tons of cargo and crew to the lunar surface.

Base construction proceeds as follows:

  * The first piloted landing by two soldier-astronauts is targeted for April 1965 near a cluster of pre-landed cargo landers. The report states that "suitable sites for the outpost exist in the northern part of Sinus Aestuum, near Erastothenes, in the southern part of Sinus Aestuum near Sinus Medii, and on the southwest coast of Mare Imbrium, just north of the Appennies [_sic_];" however, specific outpost site recommendations await completion of Army mapping programs. 

  * A nine-man construction contingent spells the first two-man crew in July 1965. They establish a minimal "construction shack" during the first 15 days (one lunar daylight period) on the moon. At about this time, an equatorial launch site with eight pads comes on line in Brazil or on Christmas Island in the Pacific (Somaliland on Africa's east coast is also considered), and the U.S. Army Signal Corps establishes "Lunarcom" communications and tracking stations in geosynchronous orbit and around the world. 

  * Sixty-one Saturn I rockets and 88 Saturn II rockets deliver 245 tons of cargo to the moon by November 1966. The outpost becomes operational with a 12-man crew in December 1966.

The basic outpost pressurized module is an empty propellant tank 10 feet in diameter by 20 feet long. A lunar tractor buries the tanks in a trench to protect them from lunar temperature extremes. The largest outpost section consists of seven tanks housing two airlocks, barracks, a hospital, a command post/radio room, and a mess/recreation room. A laboratory section (three tanks) supports physics and biological studies. The soldiers must don space suits and cross the surface to move between the sections. Each soldier-astronaut has a hard metal suit weighing 300 pounds on Earth. Tanks containing explosives, chemicals, and waste lie exposed on the surface. Four nuclear reactors sited in pits provide electricity. The outpost has a rover in addition to the tractor. The outpost is equipped initially with about 1000 pounds of defensive weapons based on terrestrial systems, including Davy Crockett missiles and handheld Claymore mines. The latter are designed to puncture pressure suits. The report also considers lunar nuclear weapons. Total cost is $700 million per year for 8.5 years, for a total of $6.014 billion, or 2 percent of the annual defense budget.


	9. 1959:A Plan for Manned Lunar and Planetary Exploration

JPL's Ground Equipment Development Group worked on the U.S. Army Sergeant surface-to-surface missile beginning in 1955. Anticipating the conclusion of Sergeant development in 1960, JPL Senior Development Engineer Hazard prepared this report to describe a new "natural assignment" for the group - "undertake the development of equipment required for Surface Exploration of the Moon and Planets." JPL transfered from U.S. Army to NASA management soon after the agency's establishment in October 1958. Hazard quotes JPL director William Pickering, who observed that spaceflight builds national prestige, creating "added confidence in our scientific, technological, industrial, and military strength. . .in this world of the mid-twentieth century and the 'cold war' this reason has become of prime importance." He bases his report on the following piloted exploration timetable:

  * _1966-67_: "Limited lunar exploration with two men" on the moon for "only several days." Hazard states that such simple missions can be performed with planned Saturn launch vehicles using Earth-orbital refueling. 

  * _1970_ sees the "first effective lunar expedition." Ten to 12 men launch in twin crew landers atop massive Nova rockets and fly directly from Earth's surface to the moon. They explore for up to six weeks. A one-way cargo lander delivers supplies, instruments, and "moonmobile" rovers. 

  * The _early 1970s_ see a permanent moon base and a manned Mars flyby. The base, which includes a closed-loop life support system, houses 20-30 men in underground tunnels. Hazard credits JPL staffer Edwin Wald with the concept of a one-year Mars flyby mission - the concept actually originated with Gaetano Crocco (1956). 

  * The _mid-1970s_ see manned Mars surface exploration based on Von Braun's 1953 _The Mars Project_ plan. 

Hazard then lists reasons why the moon should be "the location of Man's first interplanetary adventure":

  * "The moon is a logical training ground in which to prepare for the later exploration of the planets. The conduct of operations on the moon will permit us to acquire a capability in astronautics." 

  * Lunar expeditions will be "one or two orders of magnitude easier" than Mars expeditions, Hazard estimates, because "travel times to the moon are measured in hours and days rather than months and years." Particularly daunting, he writes, is developing closed-cycle life support systems for Mars flight. 

  * "In addition. . ." Hazard writes, "a propulsion breakthrough could occur anytime; i.e., a workable new concept for a nuclear rocket engine, or some anti-gravity device" which would throw open the solar system to humans. He argues that early development of surface exploration equipment for lunar use will make it available should "a breakthrough occur in the near future." 

Hazard states that planned automated lunar probes should include abstract science instruments only on a "space available" basis - that is, "number one priority should be given to obtaining information. . .on which to base the design of the hardware that will be used in Manned Explorations." He proposes sending "a hundred material/paint samples along on one of the early unmanned probes or with the mid-1960s expedition for recovery at a later date." These would, he writes, "provide indication. . .of 'weathering'/sublimation effects that might exist in the lunar surface environment," aiding the design of lunar equipment, such as

  * _Space suit_: "The very success of any Lunar/Planetary Expedition will certainly be most dependent upon the concept and design of this item," Hazard writes. He forecasts a "dependent" suit connected by a 50-to-100-foot umbilical to an air supply on the moonmobile or lander. The suit might carry a 15-to-30-minute air supply for limited independent operations, and might evolve into a fully independent suit if power and life support system weight can be kept down. He proposes "slave connector fittings" to allow a damaged independent suit to draw air and power from a healthy suit (similar to the Buddy Life Support System umbilical first carried to the moon on Apollo 14); a "smelling salts injector" for reviving unconscious moonwalkers; fabrics resistant to spilled rocket propellants; a faceplate adapter for binoculars; and a "flying belt" capable of 5-minute flights as high as 2500 feet. The suit, he says, should permit days of continuous wear, with provisions for "eating, sanitation, itching, sleeping, resuscitation, smoking, etc." 

  * _Cargo and crew landers_ based on the splay-legged, conical 1959 Schwenk & Rosen design but with cryogenic liquid oxygen and liquid hydrogen propellants. 

  * _Moonmobile_ powered by fuel cells using leftover lander propellant. Initial models transport 2-3 men, their life support equipment, and up to 1000 pounds of equipment up to 1000 miles at five miles per hour.


	10. 1960:A Lunar Exploration Program Based on Saturn-Boosted Systems

In the summer of 1958, President Dwight Eisenhower ordered the Defense Department branch services to hand over their non-military space projects to NASA, the newly formed civilian space agency. The Army, eager to retain its foothold on the new frontier, resisted relinquishing control over its chief space and missile unit, the Army Ballistic Missile Agency (ABMA) in Huntsville, Alabama. ABMA had been responsible for launching Explorer 1, the first U.S. satellite, on a missile-derived Jupiter-C rocket (January 31, 1958). While it succeeded in delaying ABMA's transfer until July 1, 1960, the Army was compelled in late 1958 to permit NASA to ignore its chain-of-command and work directly with ABMA. In early February 1959, NASA, ABMA, and the Jet Propulsion Laboratory (JPL - another former Army unit) formed the Working Group on Lunar Exploration. On June 18, 1959, NASA requested that ABMA propose an evolutionary lunar program based on the latter's planned Saturn rocket family. ABMA's report for NASA draws on its 1959 Project Horizon study, which described a lunar fort in 1967. ABMA assumes that a Saturn B-1 rocket able to place 25 tons into Earth orbit and 16,440 pounds directly on course for the moon will become available in 1964. The 201-foot-tall, 1.15-million-pound rocket includes four stages. The eight first-stage engines - derived from the Jupiter-C rocket engine - develop 1.5 million pounds of thrust to lift the Saturn B-1 and its lunar payload off the launch pad. ABMA states that "[t]he ultimate goal of the lunar exploration program will be the establishment and operation of a manned lunar base." This goal is reached through the following steps:

  1. _Circumlunar missions_: In late 1964 a Saturn B-1 launches an automated circumlunar capsule on a flight designed to test the capsule's systems for piloted circumlunar missions. To avoid interference from the moon's gravity on this first test flight, the capsule passes no nearer than 20 lunar diameters (60,000 kilometers) from the lunar surface. ABMA calculates that the capsule's 25-centimeter telescope will reveal lunar features 150 meters across - a factor of seven improvement over Earth-based instruments. Later capsules pass within a few kilometers of the moon, yielding better results. Some carry animal test subjects that blaze a trail for astronauts that follow. Piloted circumlunar flights take advantage of "the capability of passengers to observe and interpret events and details on the lunar surface." ABMA envisions four to six automated and piloted circumlunar flights by late 1966.
  2. _Automated landers_ are of two types - "stationary packet" landers and wheeled rovers. ABMA assumes that rough landers launched on small, missile-derived rockets will precede its Saturn-launched landers to the moon. The first 2125-pound stationary packet lander arrives in early 1965. It consists of a conical instrument compartment with a disk-shaped steerable solar array on top and eight fold-out arms to prevent tipping. During flight to the moon it weighs about five tons, of which about four tons is braking propulsion. The braking rocket stage separates 60 meters above the moon and jets push it out of the lander's descent path. At the same time, a metal-bottomed "gas bag" inflates to cushion impact. The lander drops unpowered to the surface and the bag deflates to complete landing. ABMA's rover is remote controlled from Earth. Following braking rocket separation, the rover falls sideways onto the moon, its impact cushioned by a gas bag on one wheel hub, then tips over onto its tires. ABMA's rover can move equally well over deep dust or smooth rock, and can drive over boulders four feet high and up 15-degree slopes. Minimum range is 50 miles and endurance is at least one lunar day (28 Earth days). Both stationary packet lander and rover carry a television camera - a vital rover component, for it allows operators on Earth to choose its path - and a drill for collecting samples for automated analysis. ABMA plans up to two stationary packet landers in 1965, and up to two rovers in late 1965-early 1966.
  3. ABMA proposes three _piloted lunar landing_ mission modes. The first two borrow heavily from Project Horizon
  4. In _direct mode_, a four-stage, 438-foot-tall launch vehicle blasts a two-stage, 25-ton lander with a two crew directly to the lunar surface.
  5. _Earth-orbital refueling mode_ can be carried out using Saturn B-1 or Saturn-C rockets. ABMA estimates that Saturn B-1 could be ready at least five years before the giant direct-mode rocket, making it an attractive choice if a piloted moon mission is planned as early as the 1970s. However, a total of 12 Saturn B-1s are needed to place into Earth orbit the 200 tons of modules and propellants for the lunar expedition. This demands, ABMA writes, "a rather high launch rate since it would be desirable that the orbital operation be completed in a short time (less than six months)." ABMA proposes reducing to six the number of launches required by developing a larger Saturn-C rocket. The first five Saturn-Cs launch one propellant tanker each into Earth orbit. The sixth launches the unfueled moonship. The third stage of the sixth Saturn-C exhausts its propellants during ascent to Earth orbit, but remains attached to the moonship to serve as the moonship's Earth-departure stage. The tankers transfer propellants to the third stage and moonship, then the third stage blasts the moonship toward the moon.
  6. _Lunar-surface rendezvous_ sees four Saturn-C rockets launching one 6.5-ton propulsion module each directly to a single site on the lunar surface. The fifth Saturn-C launches a two-man, 6.5-ton capsule directly to the same site. On the moon, the explorers remove their capsule's expended landing propulsion system and replace it with the four pre-landed propulsion modules. These then ignite to launch the crew capsule back to Earth. (JPL proposed a similar plan about a year later during the Apollo mission mode debate. ABMA judges lunar-surface rendezvous to be "feasible," but reports that the mode "is not considered desirable, at least for the early manned landing attempt."

ABMA suggests several candidate lunar landing sites. The first stationary packet lander lands in Oceanus Procellarum, near the craters Kepler and Landsberg. Rover sites include southern Mare Imbrium near the craters Stadius and Copernicus, where Earth-based observers have mapped many crater chains; Straight Wall, an 800-foot-high cliff in Mare Nubium; Alphonsus, a 70-mile-diameter crater with a 7000-foot-high rim and a central peak from which gas is said to issue; Mare Frigoris near Aristoteles, most northerly of ABMA's proposed sites; and several regions in Mare Imbrium, including Palus Putredinus and the Apennine Mountains, where Apollo 15 would land 11 years after ABMA completed its study.


	11. 1960:A Conceptual Design for a Manned Mars Vehicle

Philip Bono is a "Space Vehicle Design Specialist" for the Boeing Airplane Company Aero-Space Division. At liftoff, his eight-man Mars ship consists of:

  * 125-foot-long delta-winged glider with a 95-foot wingspan and a nose-mounted nuclear reactor for electrical power. It resembles the Defense Department's proposed DynaSoar boost glider, under development at this time, though is much larger. Bono's description of the glider's aerodynamic performance at Mars is based on an estimated martian surface air pressure about 8 percent of Earth's - the true figure is now known to be less than 1 percent of Earth pressure. 

  * Cylindrical living module 45 feet long and 18 feet in diameter with attached rocket stage. The rocket stage contains a cluster of 20,000-pound-thrust Pratt & Whitney Centaur engines. The glider's tail rests on top of the living module - a narrow tunnel links the vehicles. 

  * Seven cryogenic liquid hydrogen/liquid oxygen boosters with 1.5-million-pound-thrust plug-nozzle engines. Six boosters are clustered around the central, seventh booster, which is shorter than the others. The living module sits on top of the central booster.

At launch the Mars ship is 248 feet tall, 82 feet wide, and weighs 8.3 million pounds . Bono targets launch for May 3, 1971. The mission occurs as follows:

  * _First-stage operation_: The seven plug-nozzle engines ignite at the same time and power up to 10 million pounds of thrust. Four of the outer boosters supply propellant to all seven engines. The Mars expedition ship lifts off and climbs to 200,000 feet, where it casts off the four expended boosters. 

  * _Second-stage operation_: The three remaining engines continue to fire. The two remaining outer boosters supplying all propellant. They push the vehicle to an altitude of 352,000 feet before expending their fuel, then detach. 

  * _Third-stage operation_: The shorter central booster places the glider and living module with attached rocket stage on a trans-Mars trajectory. 

  * _Coast to Mars_: The living module deploys a 50-foot inflatable parabolic antenna for radio communications with Earth. During the 259-day Mars voyage the crew breathes a 40 percent oxygen/60 percent helium atmosphere. They point the glider's nose at the Sun to shield the living module rocket stage from solar heating. 

  * _Mars landing_: On January 17, 1972, the expedition reaches Mars. The entire crew straps into the glider. A 20,700-pound capsule containing body waste is ejected and the glider separates from the living module. The unmanned living module automatically performs a Mars orbit-insertion burn using its attached rocket stage while the glider carries the 8-man crew directly into Mars' atmosphere. It uses a drag parachute to reduce speed. At an altitude of 2000 feet ("adequate to clear the highest mountain of Mars") three landing engines fire to slow the glider to a hover. It touches down on skids with its nose pointed 15 degrees above the horizon. 

  * _Mars Operational Phase_: The explorers set up a 20-foot-diameter inflatable dome. They remove the glider's nose-mounted reactor and relocate it several thousand feet away, where it provides power to the base camp during the 479-day Mars surface stay. The crew explores and moves equipment using a 4000-pound rover. 

  * _Mars Launch_: The crew reconfigures the glider for launch by moving the landing hover engines so they can be used for liftoff. They also return the reactor to the glider's nose. The forward portion of the glider lifts off using the aft portion as a launch pad. The glider's wings provide lift, reducing the amount of propellant and size of engines needed to reach orbit. 

  * _Return to Earth_: The forward portion of the glider docks tail-first with the living module. The crew uses the living module rocket stage to leave Mars orbit on October 21, 1973. On January 24, 1974, the spacecraft encounters Earth. The glider separates from the living module and discards its nose-mounted nuclear reactor - these burn up in Earth's atmosphere - then enters the atmosphere and glides to a desert landing on skids.


	12. 1961:Convair Apollo study

In August 1959, the first U.S. manned spacecraft, Mercury, was still more than two years from flight into Earth orbit. Nevertheless, NASA initiated studies of an Earth-orbital spacecraft to replace it. In addition to flying Earth-orbital missions, the new vehicle would perform a piloted lunar-orbital flight by 1970. NASA announced the program to U.S. industry - and named it Apollo - in late July 1960. On November 15, 1960, the agency awarded Apollo feasibility study contracts to General Electric ,Martin, and the Convair Division of General Dynamics. This report covers Convair's proposed Apollo spacecraft. The design consists of the following five modules (top to bottom):

  1. The 2378-pound _abort tower_ contains a solid-fuel escape rocket with four nozzles. The abort tower plucks the Command Module free of the rest of the spacecraft if a launch vehicle emergency occurs during launch and ascent through Earth's atmosphere. 

  2. The 5648-pound _Command Module_ is half-cone lifting body ("M-1"-type) with four aft-mounted steering flaps. It is 11.2 feet long, 12.5 feet wide, and contains 340 cubic feet of pressurized volume. At launch the lifting body's blunt nose points down toward the pad. Three astronauts recline in couches facing aft (up on the launch pad). The commander pilots the Convair Apollo from the left couch with the aid of a 96-pound guidance computer. The abort tower attaches to the Command Module's aft end. 

  3. A hatch above the Command Module's center couch leads to the 3264-pound _Mission Module_, the crew's primary living and working space during spaceflight. The Command Module nests inside the Mission Module against one wall to leave a U-shaped, 1626-cubic-foot volume for the crew. This means that the Command Module's aft end protrudes from the Mission Module's forward end off-center, so the abort tower stands off-center relative to the spacecraft (and launch vehicle) long axis. Measuring 12 feet high and up to 15.5 feet wide, the Mission Module includes two windows, two control stations, galley, toilet, and the hatch for entering the spacecraft on the pad. Mission Module and Command Module contain an oxygen-nitrogen atmosphere at 14.7 pounds per square inch (Earth sea-level pressure). Four square solar panels unfold from behind the Mission Module to provide auxiliary electrical power in orbit. 

  4. The _Propulsion Module_ takes different forms depending on mission requirements. For lunar-orbital flights the Propulsion Module weighs 7088 pounds fully fueled and includes toroidal liquid oxygen and liquid hydrogen tanks feeding two Whitney XLR-115 main engines. Only one engine is needed for most manuevers - the other stands by as backup. Boil-off from the propellant tanks supplies fuel cells in the Mission Module, the Convair Apollo's main electricity source. 

  5. The cylindrical, 265-pound _adapter_ covers the Propulsion Module during launch and ascent and links the spacecraft to the launch vehicle; for lunar-orbital flight, the adapter links Convair Apollo to a 216-foot-tall Saturn C-2 rocket.

Lunar-orbital flights occur as follows:

  1. The Saturn C-2 rocket lifts off from the Atlantic Missile Range in Florida. First and second stages fall away in turn as they deplete their propellant. Convair cites launch abort recovery areas in the Atlantic and Indian Oceans. The abort tower jettisons halfway through second stage operation. The third stage injects Convair Apollo into low-Earth parking orbit. 

  2. At the proper place in Earth orbit the third stage ignites a second time to launch Convair Apollo toward the moon. The spacecraft then separates, discards the adapter, and unfolds solar panels and antennas. 

  3. The spacecraft, now consisting of the Command, Mission, and Propulsion modules, performs mid-course corrections en route to the moon based on tracking information supplied from Earth. 

  4. Convair Apollo reaches "periselenium" (closest point to the moon) behind the moon and fires its rocket to slow down and enter 50-mile-by-1100-mile elliptical lunar orbit. 

  5. Lunar-orbital mission complete, Convair Apollo's Propulsion Module fires at periselenium to push the spacecraft out of lunar orbit toward Earth. 

  6. During final approach to Earth the Command Module separates and positions itself for reentry. The astronauts face away from the nose during reentry (as they did during launch), so experience deceleration forces through their backs. The Command Module has an ablative heat shield - that is, it is covered with material that chars and breaks away, taking away the heat produced by atmospheric friction. 

  7. The Command Module deploys a stabilizing parachute as it drops past 65,000 feet. Above 15,000 feet the pilot deploys Convair Apollo's 84-foot-diameter "glidesail" parachute. Landing bags inflate automatically. Land landing is preferred - the lifting body's crushable honeycomb nose strikes the ground first, absorbing impact shock, then the parachute separates and the Command Module tips onto its landing bags. Convair cites as primary landing site Texas south of San Antonio, with backup sites at Woomera in southern Australia and Manus Island, near New Guinea.

Convair proposes the following flight program, which it estimates will cost $1.25 billion:

  * _1965-66:_ Five low-Earth-orbital flights (two last 14 days). 
  * _1967:_ Two "Earth probe" flights (one ascending 50,000 miles from Earth, the other reaching out 80,000 miles) and two circumlunar flights. 
  * _1968:_ One circumlunar flight and four lunar-orbital flights lasting between 6 and 8.6 days. 

Convair then describes how its Apollo can accomplish "advanced" missions:

  * Two Convair Apollos can perform _rendezvous & docking_ by deploying accordion-type extendible airlocks from their sides. The airlocks partially collapse to absorb docking impact, hook onto each other, then retract to bring the vehicles together. 

  * _Lunar landing_: The Convair Apollo Command and Mission Modules could be placed on top of descent and ascent rocket stages and launched directly to the moon on a heavy-lift rocket such as NASA's proposed Nova. Moonwalkers would exit the Mission Module through an accordion-type airlock and descend a rope ladder to the lunar surface.


	13. 1961:General Electric Apollo study

In January 1960, NASA released a 10-year plan for space activity that scheduled a moon landing for some time after 1970. The program meant to follow Project Mercury was conceived as primarily Earth orbital with application to "lunar reconnaissance" - that is, missions in lunar orbit. This Earth/lunar-orbital program was named Apollo in July 1960. On November 15, 1960, NASA awarded six-month Apollo feasibility study contracts to Martin Company, Convair Division of General Dynamics, and General Electric (GE). GE's recommended configuration is designed for launch on a Saturn C-1 or Saturn C-2 rocket (C-1 first flew in 1964 as the Saturn I, while the C-2 variant was never built). GE Apollo includes three modules - fore to aft they are

  * the _mission module_, the main in-flight living and working space, with "astrodome" navigation equipment, backup manual navigation equipment, radar altimeter, infrared sensors, instrument panel/control console, secondary breathing gas (oxygen and nitrogen) supplies, toilet, galley, and recreation equipment. A hatch leads aft into the 

  * _reentry vehicle (RV)_, which contains the main spacecraft instruments/controls and life support systems, landing parachutes, and acceleration/deceleration couches for two or three astronauts. The crew rides in the RV during ascent to orbit and Earth atmosphere reentry. The RV's wide blunt end includes a heatshield. GE recommends the RV's "blunt body semi-ballistic" approach "because of [its] lightweight design, high degree of system reliability, known state-of-the-art[,] and earliest possible development schedule." The RV and command module are housed within a "cocoon" outer shell to protect against air leaks caused by a meteor penetration (GE estimates that this might occur once in 640 missions). Crew access and egress is through a side hatch. 

  * The _propulsion module_ flares at the back to the anticipated diameter of the C-1 and C-2 launchers. It contains one large spherical liquid hydrogen fuel tank and four smaller spherical liquid oxygen oxidizer tanks, four main engines, and a deployable round solar "collector." GE proposes "underfueling" a single propulsion module design for different missions rather than building different specialized propulsion modules. Different propellant loads mean different weights - for an Earth-orbital flight GE Apollo weighs 12,000 pounds at Earth launch; for a circumlunar flight, 16,558 pounds; and for a lunar-orbital mission, 20,520 pounds.

At the end of a normal flight eight small solid-propellant rockets separate the propulsion module from the RV and eight more separate the command module. The RV then positions itself for reentry with its heatshield forward. In the event of abort off the launch pad or during ascent, eight solid-propellant abort rockets attached to the outside of the propulsion module push the GE Apollo spacecraft free of the malfunctioning booster, then four large solid-propellant separation rockets on the command module pull it and the RV free of the propulsion module. The RV then detaches from the command module, drops free of the cocoon outer shell, and pops its parachute for landing.

GE envisions a 29-flight Apollo program spanning late 1963 to early 1968, which includes the following milestones:

  1. _Third quarter 1964 (flight 7):_ First unmanned Earth-orbital flight. 

  2. _Second quarter 1965 (flight 11):_ First manned Earth-orbital flight. 

  3. _First quarter 1966 (flight 21):_ First manned cislunar (150,000-mile elliptical Earth orbit) flight. 

  4. _Fourth quarter 1966 (flight 23):_ First manned circumlunar (lunar swing-by) flight. 

  5. _Second quarter 1967 (flight 26):_ First manned lunar orbital flight.


	14. 1961:LUNEX

Soon after the Soviet Union launched Sputnik 1 on October 4, 1957, the U.S. Air Force launched "Lunar Observatory" and "Strategic Lunar System" studies. The sky no longer seemed the limit for Air Force pilots. On October 1, 1958, however, the Eisenhower administration created the civilian National Aeronautics and Space Administration (NASA) and charged it with directing Project Mercury, the U.S. effort to launch a human into orbit. This was done in part to prevent piloted spaceflight - seen by many as a one-off stunt to garner prestige - from interfering with more consequential Defense Department space programs, such as missile and surveillance satellite development. On April 12, 1961, the Soviet Union launched Vostok 1, beating the U.S. to the goal of launching the first human into orbit. The Kennedy administration responded on May 25, 1961, by calling for an American on the moon by the end of the 1960s. Four days later, the Air Force released this report (classified "Secret"). The report identifies the following "major 'prestige' milestones" for the proposed Air Force Lunar Expedition (LUNEX) program:

  1. _April 1965:_ First manned Earth-orbital flight of the LUNEX Reentry Vehicle. 
  2. _September 1966:_ First manned circumlunar flight. 
  3. _August 1967:_ First manned lunar landing and return. 
  4. _January 1968:_ Establish permanently manned lunar expedition base.

The workhorse of the LUNEX program is a three-stage Space Launching System booster rocket capable of launching 350,000 pounds into Earth orbit 300 miles high, 134,000 pounds directly to the moon, or a manned vehicle on Mars or Venus flyby path. The report describes an elaborate seaside launch facility, to which rocket components are delivered by barge. Candidate launch sites include Cape Canaveral, Florida; Port Arguello, California; Corpus Christi, Texas; and the Georgia and South Carolina coasts. The Space Launching System is used to launch two types of moon landers:

  * The automated _Cargo Payload_ spacecraft consists of (bottom to top) a Lunar Landing Stage and a cargo package weighing up to 45,000 pounds. The Cargo Payload reaches the moon ahead of the piloted Manned Lunar Payload spacecraft bearing equipment and supplies for lunar exploration. 

  * The _Manned Lunar Payload_ spacecraft consists of (bottom to top) a Lunar Landing Stage, a Lunar Launch Stage, and a LUNEX Reentry Vehicle. The Manned Lunar Payload, "the largest single development objective of the LUNEX program," measures 52 feet, 11 inches long, and is 25 feet in diameter at the bottom of the Lunar Landing Stage, where it interfaces with the Space Launching System. The 20,205-pound LUNEX Reentry Vehicle is a triangular lifting body with twin tail fins and twin winglets.

The LUNEX mission occurs as follows:

  1. _Launch_: The three LUNEX crew members enter the Manned Lunar Payload through a hatch in the top of the LUNEX Reentry Vehicle. They recline in the forward section of the lifting body in three couches, one below the other, facing upward toward the lifting body's nose. The Space Launching System places the Manned Lunar Payload on a direct course for the moon. Abort options include separating the LUNEX Reentry Vehicle and gliding to a nearby runway. 

  2. _Earth-moon transit_ lasts two and a half days. 

  3. _Descent and landing_: The Manned Lunar Payload is piloted from the lowermost couch for descent toward the lunar surface. During final descent the couch tips 90 degrees, pointing the pilot's feet toward the moon. The conical Lunar Landing Stage includes four engines and four landing feet shaped like cylindrical tanks with hemispherical end caps. It lands near a pre-landed Cargo Payload lander. Abort options include blasting free of the Lunar Landing Stage using the Lunar Launch Stage and using the single Lunar Launch Stage engine to carry out a dangerous rough landing. In the latter case the crew would abandon their Manned Lunar Payload and transfer to a pre-landed Manned Lunar Payload for flight home to Earth. 

  4. _Lunar surface exploration_: On the lunar surface "up" is toward the Manned Lunar Payload's nose. The aft section of the LUNEX Reentry Vehicle includes two decks, one atop the other, providing living quarters for the crew. A hatch in the lower deck floor leads "down" through the lifting body's tail end to an airlock in the Lunar Launch Stage. The airlock in turn leads to the lunar surface through a hatch in the side of the Lunar Launch Stage. Surface exploration during the first landing mission lasts about five days. 

  5. _Lunar liftoff & moon-Earth transit_: The Landing Stage acts as launch pad when the Lunar Launch Stage blasts the LUNEX Reentry Vehicle off of the moon. No abort options exist for this phase of the mission - the Lunar Launch Stage must be built to ensure high reliability. Moon-Earth transit lasts two and a half days. 

  6. _Earth reentry & landing_: The Launch Stage is cast off just before the LUNEX Reentry Vehicle reaches Earth's atmosphere. For Earth landing the pilot sits in the forward couch. As reentry deceleration ends and gliding flight begins, the pilot ejects heatshields covering the forward window and the landing wheels, then guides the lifting body to an unpowered landing on a runway at Edwards Air Force Base, California.

The report recommends that the LUNEX piloted mission be preceded by an automated lunar orbiter (such as NASA's proposed Lunar Orbiter) for refining lunar surface maps, which at this time included no features smaller than 16 miles across. The best telescopic photos of the moon taken from Earth showed no features smaller than one-half mile across. NASA's automated Surveyor landers could be used to land radio-light beacons on the moon to aid LUNEX pilots "[i]f expedited." The report adds that an automated lander will have to drill into the lunar surface to collect a core sample then blast it back to Earth before lunar base design can proceed. The LUNEX program, which would cost upwards of $7.5 billion by 1971 and employ about 70,000 people in industry, would have to approved by July 1961 to place the first crew on the moon in August 1967.


	15. 1961:Fleming Committee report

NASA's long-range plan of January 1960 put off the first piloted moon landing until after 1970. By late 1960, the Apollo program was conceived primarily as an Earth-orbital program aimed at piloted circumlunar flight by 1970. These plans began to change after cosmonaut Yuri Gagarin became the first man to orbit Earth (April 12, 1961). On April 20, 1961, President John F. Kennedy sent a now-famous memorandum to Vice-President Lyndon Johnson, chair of the National Space Council. He asked

> Do we have a chance of beating the Soviets by putting a laboratory in space, or by a [piloted] trip around the moon, or by a[n automated] rocket to land on the moon, or by a rocket to go to the moon and back with a man. Is there any other space program which promises dramatic results in which we could win?

Landing a man on the moon emerged as the clear favorite. NASA Associate Administrator Robert Seamans formed the Ad Hoc Task Group on May 2, 1961. He directed William Fleming of NASA Headquarters to study landing a man on the moon using Direct Ascent, in which the crew travels from the Earth to the moon in a single moon lander spacecraft. The Group's craft for circumlunar and Earth-orbital precursor flights consists of a conical Apollo capsule and a small two-engine service module together weighing 12.5-tons. For landings a large cylindrical descent stage with four engines is added, and the small service module becomes the ascent propulsion system for launching the Apollo capsule back to Earth from the surface of the moon. The Direct Ascent moon lander weighs about 75 tons fully fueled. For comparison, the Apollo Lunar Module (LM) flown from 1969 to 1972 weighed about 18 tons; the LM and Apollo Command Module together weighed less than 50 tons. The Group envisions two possible landing methods:

  * _Horizontal:_ The moonship approaches the landing site with the Apollo capsule pointed backward along its line of flight and touches down on three skids with its long axis roughly parallel to the surface. After landing, the Apollo capsule/small service module points at an angle above the local horizon. Total length is about 57 feet. 

  * _Vertical:_ The moonship lands on three landing legs with its long axis perpendicular to the surface. Total height is about 58 feet and spread across the legs is 38 feet. (Lander dimensions are taken from technical drawings of the proposed vehicle in the Apollo archives at Rice University.) 

The Fleming group then lays out a detailed timeline for the 167 flights it says are needed to accomplish a manned moon landing in 1967. These include:

  1. automated Ranger hard lander and photography missions to the moon approximately every third month from July 1961 to October 1963 (11 missions)
  2. 14-day biomedical flights by animals in Mercury-Atlas vehicles every other month from January 1962 to July 1963 (9 missions)
  3. 18-orbit piloted Earth-orbital missions using Mercury-Atlas every other month from April 1963 to April 1964 (7 missions)
  4. Surveyor lander and orbiter missions to the moon approximately every other month from July 1963 to November 1966 (14 missions)
  5. first reentry test of an automated prototype Apollo capsule in December 1963
  6. piloted suborbital and orbital Apollo qualification tests approximately every month from October 1964 to September 1965 (8 missions)
  7. piloted elliptical Earth-orbital and circumlunar missions approximately every month beginning in November 1965 (9 missions)
  8. first test launch of complete Nova rocket in August 1966, possibly from a new launch site on Cumberland Island off the coast of southern Georgia
  9. piloted lunar landing flights in August 1967 and December 1967 (2 missions)

The Fleming committee estimates the cost of the program at nearly $11.7 billion dollars.


	16. 1961:Earth Orbit Rendezvous mission studies

Even before President John Kennedy's May 1961 call for a man on the moon, three competing modes for carrying out a manned moon voyage emerged within NASA - Direct Ascent, Lunar-Orbit Rendezvous (LOR), and Earth-Orbital Rendezvous (EOR). Direct Ascent was first out of the gates and LOR was the dark horse (which eventually won). Many - including Werner von Braun, NASA Marshall Space Flight Center director - saw EOR as desirable because the "building block" technique it pioneered could be used in future to build up large Earth-orbital space stations and interplanetary ships. In EOR, the Apollo lunar spacecraft performs rendezvous and docking in Earth orbit with separately launched propulsion modules. These then ignite to place the Apollo on course for the moon. EOR thus removes the need to develop Direct Ascent's very large heavy-lift rocket. This report constitutes a follow-on to the Lundin Committee report, and was designed to apply to EOR the same advisory committee approach that the Fleming Committee brought to Direct Ascent. U.S. Air Force Colonel D. H. Heaton chaired the EOR group, while John Houbolt (NASA Langley Research Center), the leading advocate of all types of rendezvous and of LOR in particular,chaired the Orbital Launch Operations sub-panel. The Heaton Committee describes several versions of its EOR lunar expedition; the following may be taken as representative.

  * _Launch propulsion modules:_ Four Saturn C-3 rockets launch one R-3 propulsion module each. The Saturn C-3 is a 178-foot-tall, three-stage rocket weighing 2.4-million pounds. The first stage includes two F-1 rocket engines; the second stage has four J-2 engines; and the third stage includes six A-3 engines. Saturn C-3 can launch 105,000 pounds to 250-kilometer Earth parking orbit. The R-3 propulsion modules measure 60 feet long by 15 feet wide and weigh 105,000 pounds loaded with cryogenic (supercold) liquid hydrogen/liquid oxygen propellants. R-3 includes one J-2 main engine, twelve smaller engines for rendezvous and docking maneuvers, a radar transponder for docking target homing, and fore (active) and aft (passive) docking units. Each R-3 parks with its aft docking unit and J-2 pointed at the Sun - this shields its cryogenic propellants from solar heating, helping forestall boil-off. 

  * _Assembly:_ A fifth C-3 launches the 52,500-pound manned Apollo lunar spacecraft to 485-kilometer rendezvous orbit. The astronauts aboard the Apollo "call up" R-3 #1. The R-3's climb from parking orbit to rendezvous orbit requires 45 minutes. R-3 #1 docks with Apollo's aft end, which faces in the direction of orbital motion. The next day the crew calls up R-3 #2, which docks to R-3 #1's aft end. The remaining R-3s dock on successive days to form a 450,000-pound "stack" of modules 280 feet long. 

  * _Earth-orbit departure:_ The lunar vehicle rotates end for end to put the Apollo spacecraft at the front end of the stack. Upon reaching the proper point in Earth orbit relative to the moon, R-3 #4 fires its J-2 engine until its depletes all its propellants, then undocks. R-3 #3 and R3 #2 repeat this sequence, placing R-3 #1 and the Apollo spacecraft on course for a 60-hour lunar voyage. 

  * _Lunar orbit arrival and landing:_ R-3 #1 slows Apollo so the moon's gravity can capture it into orbit, then separates. Apollo's engine burns storable propellants (for example, hydrazine and nitric acid) to slow down and drop from lunar orbit. Apollo can hover for 2 minutes during final surface approach while its pilot seeks a suitable landing spot. 

  * _Return to Earth:_ Apollo lifts off the lunar surface and flies directly back to Earth. The Heaton Committee provides few details on this portion of its proposed mission.

The report notes that an EOR mission plan using a larger rocket, the Saturn C-4, "should offer a higher probability of an earlier successful manned lunar landing" because it involves fewer launches and less rendezvous. The report shows Houbolt's influence - for example, it proposes a rendezvous and docking demonstration in Earth orbit using the Mercury Mark II maneuverable two-man spacecraft and an Agena B target vehicle. Such a demonstration, the report contends, is necessary regardless of which Apollo mode is selected because rendezvous and docking are essential spaceflight techniques - they will, for example, be needed to transfer crews to space stations. The Heaton Committee proposes the following schedule for its EOR Apollo lunar program:

  1. _1963-64:_ Rendezvous and docking demonstration flights
  2. _1965:_ R-3 module and Apollo spacecraft tests in Earth orbit
  3. _Early 1966:_ First circumlunar flight attempt
  4. _Late 1966:_ First lunar landing attempt

The Heaton Committee estimates the cost of its EOR plan at $10.2 billion - $1.5 billion less than the Fleming Committee's estimate for Direct Ascent.


	17. 1961:Mars landing studies

Robert Lowe and Robert Gervais are breathtakingly optimistic about the rate of progress in spaceflight technology. Though they state that "the purpose of this analysis is to present feasibility within the present state of the art" and that "the time span of this investigation is restricted to within the next decade," their report describes a spaceship capable of ascent to Earth orbit without dropping spent propulsion stages - that is, a single-stage-to-orbit ship. What's more, after performing this impressive feat (still not achieved 40 years on), their ship carries three men to Mars or Venus and returns them to Earth. Their ship weighs 125 tons at Earth launch and stands 137 feet tall. Shaped like a missile warhead (or badminton shuttlecock), it measures 86 feet across its base and 10 feet across its dome-shaped nose. The Mars expedition occurs as follows:

  1. _November 6, 1971 - Earth launch and Earth-orbit departure:_ The ship's single solid-core nuclear rocket engine heats and expels hydrogen propellant to generate 1.5 million pounds of thrust, pushing the ship off the launch pad. Though the engine shuts down at 90 miles altitude, hydrogen continues to pass through the reactor for cooling. This "cooldown" thrust places the ship into 300-mile-high circular orbit with nearly empty tanks. It docks nose-on with a cluster of seven 40-foot-diameter, 123-foot-long hydrogen tanks. Together ship and tank cluster weigh 568 tons. The engine ignites a second time to blast the ship and tank cluster out of Earth orbit. 

  2. _May 22, 1972 - Mars arrival and landing:_ After 198 days the ship arrives at Mars. The astronauts discard the tank cluster, briefly fire the nuclear rocket engine to cut speed, then aerobrake in Mars' atmosphere and descend directly to a powered landing on Mars. For their Mars entry calculations Lowe and Gervais assume an atmosphere roughly 10 percent as dense as Earth's (true density is less than 1 percent). The crewmen feel less than three Earth gravities of deceleration during aerobraking and landing. 

  3. _August 30, 1972 - Mars departure:_ After 100 days on Mars the ship lifts off for Earth return. Mars' gravity is only 39.7 percent of Earth's, so the engine need generate only 350,000 pounds of thrust. 

  4. _December 15, 1972 - Earth arrival:_ At the end of a 107-day Mars-Earth transfer the ship fires its engine briefly to slow down, aerobrakes in Earth's atmosphere, and lands. The crew experiences less than three Earth gravities of deceleration.


	18. 1961:Lunar orbit rendezvous studies

This handout, originally classified "Confidential," does not name its author - however, other sources indicate that it was prepared by NASA Langley Research Center (LaRC) engineer John Houbolt. The Space Task Group (STG), which heard Houbolt's briefing, was officially established on November 5, 1958, to conduct Project Mercury, the first U.S. piloted space program. Following President Kennedy's May 25, 1961 "Moon speech," the STG's responsibilities expanded to encompass putting a man on the moon. Though the STG got its start at LaRC, Houbolt was never an STG member. His "high risk lunar landing program" is not meant to replace the programs proposed by Fleming and Lundin - in fact, the handout states that the U.S. "can only afford to take risks if there is another more conservative program in being." It adds, however, that "[i]f risks pay off [it] can be much _faster_" and cheaper than the other proposed programs. Total cost is estimated at only $584.3 million. The Titan II rocket is the program workhorse, launching the Mark II, lunar lander, and Centaur into low-Earth orbit. The Agena launches on Atlas. The two lunar orbital missions (one of which includes the first landing) require the Saturn C-3 rocket. Over 2 years, 10 months the program proceeds through the following phases:

  * _Mercury Mark II spacecraft qualification_: The Mark II depicted in the handout is an early version of the two-person spacecraft NASA officially named Gemini in January 1962. Assuming a September 1 authorization to proceed, an unpiloted flight test occurs in March 1963, followed by an 18-orbit piloted test in May 1963. 

  * _Long-duration tests_: Two missions in Earth orbit in July and September 1963 suffice to prove that astronauts and the Mark II can withstand a seven-day lunar flight. 

  * _Rendezvous and docking with Agena_: Agena is an unpiloted upper stage/rendezvous target. Rendezvous is considered a major spaceflight challenge, so the program sets aside three Titan II-Mark II and three Atlas-Agena flights to develop this capability (November, 1963; January, March 1964). 

  * _Deep space exercise_: This includes two flights in May and July 1964, each involving a rendezvous and docking in low-Earth orbit between a piloted Mark II spacecraft and a separately launched unpiloted Centaur upper stage. The latter launches the Mark II into an elliptical orbit with a 50,000-mile apogee. 

  * _Rendezvous between Mark II and lunar lander_: The lander is a one-person pressurized vehicle. The unpiloted lander and piloted Mark II reach low-Earth orbit separately on Titan IIs then rendezvous and dock. The Mark II carries a probe which inserts into the lander engine bell for docking. During the third flight in January 1965, one astronaut spacewalks between the Mark II and the lander after docking. 

  * _Circumlunar flights_: In March and May 1965, a Mark II spacecraft makes rendezvous and docks with a Centaur upper stage in low-Earth orbit. The Centaur pushes the Mark II onto a lunar free-return trajectory - that is, it swings around the backside of the moon and falls back to Earth. 

  * _Lunar orbit reconnaisance_: For this lunar orbital mission in November 1965 a lander and Mark II launch on a Saturn C-3 rocket. The lander rides to the moon inside a shroud behind the Mark II. The lander's engine inserts the combination into a circular 50-mile lunar orbit. The handout fails to make obvious whether the lander plays any other role in this mission. In any case, the lander is discarded before the Mark II uses its main engine to leave lunar orbit. The Mark II discards its main propulsion system but retains a smaller propulsion system, presumably for course corrections. This is discarded prior to atmosphere entry. 

  * _Lunar landing_: In January 1966, a Saturn C-3 rocket boosts the Mark II and lander to the moon. Total weight inserted into a lunar free-return trajectory is 27,320 pounds. The lander engine inserts the combination into lunar orbit, then one astronaut spacewalks from the Mark II to the lander's small cabin. The lone astronaut detaches the 10,690-pound lander, casts off the tanks that held lunar orbit insertion propellant, then fires its rocket to descend to the surface. He hovers for up to 60 seconds before landing on four oversized footpads. Landed weight is 4600 pounds. The astronaut performs a moonwalk, then returns to the lander and fires its rocket to return to lunar orbit. The Mark II inserts its probe into the lander engine bell and the astronaut spacewalks back to the Mark II. The lander is then cast off and the Mark II fires its main engine to return to Earth.

—————

Following President Kennedy's May 25, 1961 "moon speech," NASA planners re-directed Project Apollo. Originally it was to be a manned Earth-orbital program leading to an eventual circumlunar or lunar orbital flight; now it would land a man on the moon by the end of the 1960s. But how would Apollo accomplish this feat? The process by which the Apollo mode decision was taken was complex and involved many players, many of whom backed different modes at different times. Throughout the process, Langley Research Center (LaRC) engineer John Houbolt staunchly advocated Lunar-Orbit Rendezvous (LOR), the mode which, after its adoption in July 1962, made possible attainment of Kennedy's goal just seven years later. The LOR concept dates at least as far back as 1948, when H. E. Ross described it before a meeting of the British Interplanetary Society. Houbolt gave briefings on LOR to several groups involved in the Apollo mode decision, including the Lundin Committee and the Ad Hoc Task Group for Study of Manned Lunar Landing by Rendezvous Techniques (Heaton Committee). The Large Launch Vehicle Planning Group (Golovin Committee) requested this report after Houbolt briefed it in August 1961. The LOR mission vehicle consists of:

  * _Apollo spacecraft_ including an Earth-atmosphere reentry vehicle. The report considers Apollos weighing 8500 pounds, 11,000 pounds, and 12,500 pounds. 

  * _Lander ("Bug"):_ LaRC considers three designs for its single-stage lander: 

    * The "shoestring" lander places one man (200 pounds including space suit) on the moon and returns him to the Apollo spacecraft after only a brief surface stay. It weighs 1270 pounds without propellants; 4100 pounds with hydrogen/fluorine (H/F) propellants; 4200 pounds with hydrogen/oxygen (H/O); 6200 pounds with hydrazine/nitric acid (storable propellants); and 7900 pounds with solid fuel. H/F is most energetic propellant combination but is hardest to handle; solid fuel is least energetic but easiest to handle. The shoestring Bug can return 50 pounds of samples to the orbiting Apollo. 

    * The "economy" lander supports two men during a 24-hour lunar surface stay. It weighs 2234 pounds dry, 7250 pounds loaded with H/F, 7500 pounds with H/O, 10,800 pounds with storables, and 13,900 pounds with solid fuel. It can lift 100 pounds of samples to the orbiting Apollo. 

    * The "plush" lander supports two men on the moon for one week. It weighs 3957 pounds dry, 12,750 pounds loaded with H/F, 13,300 pounds with H/O, 19,100 pounds with storables, and 24,600 pounds with solid fuel. The Plush Bug can lift 150 pounds of samples to the Apollo.

According to LaRC, LOR landing is safer than landing in other modes because its lander is designed only for that function - in other modes the landing function is compromised to take into account other functions, such as Earth reentry. Typically the LOR mission vehicle includes only one lander, but LaRC also describes a configuration with two shoestring landers. If the first is unable to rendezvous with the Apollo in lunar orbit the second mounts a rescue mission.

  * Two _propulsion modules:_ The larger module burns H/O propellants to place the LOR mission vehicle onto an Earth-moon transfer trajectory (see #3 below); the smaller burns H/F, H/O, storables, or solid propellants to slow the spacecraft so the moon's gravity can capture it into lunar orbit (see #5 below), then places the Apollo spacecraft onto a moon-Earth transfer trajectory (see #8 below).

LOR mission vehicle weight in Earth orbit ranges from just 56,000 pounds for a shoestring lander and 8500-pound Apollo burning H/F propellants to 196,300 pounds for a plush lander and a 12,500-pound Apollo burning solid fuel. The LOR expedition does not stand in isolation - as with other proposed Apollo modes, it is achieved only after many preparatory missions. LaRC's proposed "Master Flight Plan" includes the following manned and unmanned missions:

  * _Ranger_ automated lunar rough-landing missions - 11 landings between January 1961 and October 1963. These help to characterize the lunar surface ahead of the arrival of astronauts. 

  * _Mercury_ manned Earth-orbital missions, each completing 18 Earth orbits - four missions between February and August 1963. These gather basic data on human spaceflight performance. 

  * _Surveyor_ automated lunar soft-landing missions - 15 landings between August 1963 and March 1966. 

  * Apollo reentry vehicle dropped from aircraft to test glide characteristics, parachutes, and land landing systems - 20 tests between September 1963 and June 1964. 

  * _Earth-orbit rendezvous_ between a manned Mercury Mark II spacecraft and a separately launched unmanned Agena target vehicle - five missions between October 1963 and June 1964. These give the astronauts experience with rendezvous and docking. (Mercury Mark II became known as Gemini in January 1962.) 

  * _Earth-orbit rendezvous_ between a manned Mercury Mark II and an LOR Bug lander, launched together on a Saturn C-1 rocket - six missions between August 1964 and June 1965. 

  * _Earth-orbit rendezvous_ between a manned Apollo spacecraft and an LOR Bug, launched together on a Saturn C-1 - two missions in September and October 1965. 

  * Manned _Apollo suborbital and Earth-orbit flight tests_ launched on Saturn C-1s - eight between September 1964 and August 1965. 

  * Manned _Apollo high elliptical Earth-orbit and circumlunar/lunar-orbit missions_ launched on a Saturn C-3 or Saturn C-4 rocket - four between November 1965 and February 1966. These could be made into manned lunar landing attempts. 

  * Manned _lunar landing expeditions_ launched on Saturn C-3s or C-4s - four landing attempts between March and June 1966.

The LOR lunar landing expedition, the culmination of LaRC's five-and-a-half-year program, occurs as follows:

  1. _Launch:_ Cape Canaveral, Florida is the launch site selected for all Apollo expeditions, regardless of mode selected. 

  2. _Establish Earth orbit:_ Direct flight to the moon from a fixed Earth site can begin only during a short period each month. To avoid this limitation, the LOR mission vehicle enters low-Earth orbit before setting out for the moon. In effect this gives the expedition a mobile launch site, providing mission designers with "complete freedom" in selecting expedition start time. 

  3. _Injection into Earth-moon trajectory:_ LaRC notes that a fast trip to the moon requires that the LOR mission vehicle use a great deal of propellant to slow down and enter lunar orbit. LaRC opts for a Earth-moon transfer lasting from 2.5 to 3 days, noting that this transfer trajectory "can be designed as a free return circumlunar trajectory, which would be utilized if a. . .malfunction prohibited going into lunar orbit." 

  4. _Midcourse correction:_ This phase occurs in the same manner regardless of Apollo mode selected, so LaRC's report gives it little attention. 

  5. _Establish lunar orbit:_ LaRC recommends that the LOR mission vehicle aim for a 50-mile-high circular orbit over the moon's equator, "especially if the exploration time on the lunar surface is to be of the order of a week." A spacecraft in such an orbit passes over all sites on the moon's equator every two hours. This means that every two hours the Bug lander can begin descent to a given site on the moon's equator or liftoff from the surface for rendezvous with the orbiting Apollo. Sites north or south of the equator are accessible, but only by adding propellant. This is because the moon's rotation carries a non-equatorial site away from the orbiting Apollo, forcing a plane change maneuver before rendezvous can occur. LaRC judges, however, that the plane change required after a one-day stay at a non-equatorial site is "insignificant." Prior to Bug separation the crew examines the moon's surface from orbit to make final site selection. LaRC proposes that landing occur at a night-enshrouded site under a full Earth, "thus avoiding the bright glare and black shadows of the sunlit side." 

  6. _Descent from lunar orbit and lunar landing:_ One or two astronauts enter the Bug and undock. They fire its engines briefly to move away from the Apollo. This prevents the latter from being enveloped in the Bug's engine plume when the actual "lunar letdown" maneuver begins. The Bug engines - LaRC recommends two for redundancy and improved maneuvering - can be throttled and gimbaled (pivoted). The pilot performs the landing manually with instrument aids. Halfway around the moon from the selected landing site he fires the engines to slow the Bug by 60 feet second. This nudges its orbit so it intersects the surface at the landing site. The Bug coasts for an hour, steadily losing altitude. Bug and Apollo remain in visual and radio contact throughout. About 100 miles from the landing site the Bug pilot fires the twin engines to reduce speed, then commences landing maneuvers. The Bug gradually tips so it reaches the landing site with its engines pointed down. The pilot has one minute of hover time to choose a safe spot for final letdown; should landing prove impossible he can abort back to orbit. 

  7. _Return to lunar orbit and lunar-orbit rendezvous:_ Just before liftoff the orbiting Apollo climbs into view over the horizon, and the Bug pilot spots it visually and with radar. A gyroscope-equipped "inertial attitude reference" provides guidance data; if the electronic aids fail, however, the pilot can complete rendezvous and docking visually. The Bug, which uses the same rocket engines for ascent that it used for descent, climbs 10 miles high at 0.5 gravities of acceleration, then coasts for up to 33 minutes on an arcing course. Meanwhile, the Apollo passes over the landing site and pulls ahead, so the Bug approaches it from below and behind. The Bug pilot starts homing on Apollo's light beacon about 250 feet out. Docking takes place over the lunar night hemisphere to avoid sun glare and improve beacon visibility. After docking, the crew transfers to the Apollo and casts off the Bug. 

  8. _Injection into moon-Earth trajectory, midcourse correction, reentry, touchdown, and recovery:_ LaRC states that the Apollo reentry vehicle must land within the United States, and reports that studies of optimum Earth-return trajectories for accomplishing this are in progress. (This Apollo requirement was later dropped in favor of mid-ocean splashdown.)


	19. 1962:Lockheed lunar base studies

Aerospace companies in the U.S. naturally saw President Kennedy's May 1961 call for a man on the moon as a profit-making opportunity, and quickly moved to position themselves to take advantage of NASA's efforts to explore space. Lockheed Missiles and Space Company, for example, believed that Kennedy's call might lead to a permanent U.S. presence among the moon's jagged mountains and rugged craters, so launched an in-house lunar base study called Extended Lunar Operations (ELO). Results were briefed to NASA officials. Lockheed hoped that ELO would (in the short term) prepare it to conduct NASA-funded lunar base studies should the space agency decide to contract for them, and (in the long term) improve the company's chances of receiving lucrative contracts to build lunar base hardware. Other aerospace companies performed lunar base studies at the same time for the same reasons.

_Lockheed's _Lunar Traversing Vehicle_ is a "mobile station" for 1000-mile journeys across the lunar surface lasting up to two weeks. Empty weight in lunar gravity (one-sixth Earth gravity) is about 1700 pounds. Two 12-foot-diameter spherical compartments provide living and working space for up to four men. Each sphere includes a 768-pound cylindrical airlock that doubles as a solar flare shelter. Four 16-foot-diameter metal wheels with cleats provide adequate traction in lunar gravity, are less likely than pneumatic tires to suffer damage from sharp lunar rocks, and are easily maintained. They can cross crevasses up to 8 feet wide. Eight bogeys, seven of which are passive rollers, link each wheel to its sphere. The eighth has gear teeth to transmit power to the wheel from the electric drive system inside each sphere. Steering is through differential power application; that is, a left turn is accomplished by supplying less torque to the wheels on the left side. Normal speed is five miles per hour and minimum turn radius is 35.5 feet. Lunar Traverse Vehicles are used with accessories to unload and emplace lunar base modules (see below)._

Lockheed provides a detailed lunar base development program schedule spanning from 1962 to 1980. Ranger hard landers collect lunar environment data from early 1962 to mid-1965. Lunar base planning occurs between early 1962 (the start of the ELO study) and late 1964 and concept development spans early 1962 through mid-1966. Preliminary hardware design starts in mid-1963 and lasts until 1970. Surveyor A soft landers explore the moon between mid-1964 and early 1976, while Surveyor B orbiters map the surface between mid-1965 and mid-1976. Base hardware development begins in 1966, while simulations and tests to prove hardware reliability begin in mid-1967. Lockheed sees ELO as growing directly from Apollo and taking advantage of Apollo technology. Apollo B piloted circumlunar and lunar orbital missions span late 1966-early 1968. Apollo C missions (piloted moon landings with stays no longer than two days) span 1968 and 1969. The company invokes the Apollo Saturn C-5 (as the Saturn V was known in 1963), possibly with "high-energy propellants" or a nuclear third stage, as ELO's workhorse launcher. Saturn C-5s commence delivering ELO modules to the moon in 1969. Extended lunar exploration with stays no longer than two weeks span 1970 and the first half of 1971. In mid-1971, NASA establishes an "interim lunar exploratory base" supporting stays no longer than three months. This is followed, beginning in 1974, by a "semi-permanent lunar base" with stays no longer than six months. A permanent lunar base with "unlimited operations" becomes operational in 1975.

_Each ELO module reaches the moon attached to a 10.8-foot-long, 18-foot-diameter braking stage and a 12.5-foot-long, 18-foot-diameter landing stage. The braking stage places the landing stage and module into lunar orbit and separates, then the landing stage lowers the module to the lunar surface. The first ELO landings deliver two cargo modules, each containing one Lunar Traverse Vehicle with base module-handling equipment. Astronauts land nearby in one or more Apollo Lunar Excursion Modules. They inflate toroidal "bumpers" girdling the top and bottom of each cargo module (they appear black in the illustration above) and tip each module onto its side. The astronauts then uncap the cargo modules and drive the Lunar Traverse Vehicles out onto the moon. These deliveries prepare the way for arrival of the first base module._

_The first two Lunar Traverse Vehicles,linked together with module-handling equipment,unload an 18-foot-diameter, 42-foot-long base module from a landing stage, transport it to the base location, and position it on the surface. The module-handling equipment is also used to "dock" newly arrived modules with modules already in place at the base site. Base modules weigh about 28,000 pounds and arrive on the moon fully outfitted. Note the astronauts clambering over the module-handling structure more than 30 feet above the surface._

Although it offers an optimistic schedule for lunar basing, Lockheed also states that NASA's moon program will evolve through a series of key decision points, any one of which could mean the end to lunar basing efforts. The Ranger and Surveyor probes produce the first decision point: their data could cause the U.S. to end all lunar exploration, continue with automated missions alone, or ("most optimistic from a manned lunar basing point of view") launch piloted Apollo circumlunar flights to take advantage of "Man's close up observation and judgment capabilities." If piloted circumlunar reconnaissance then reveals the moon to be "unsuitable for Man," piloted exploration would likely be delayed. Otherwise, Apollo landings would occur, followed "logically" by extended operations to gather engineering data for lunar base development. These might reveal "overwhelming obstacles" to lunar bases. Assuming that no such obstacles exist, the next phase, "Early Manned Basing," will seek potential lunar resources. Extensive permanent basing focused on exploiting resources might follow. Evolutionary decision points aside, NASA's lunar program might end at any time because of "diversion of funding to other efforts," such as "interplanetary travel" ,or because of a "drastic change in politico-economic philosophy" in the United States.


	20. 1962:a supply truck for the Moon

Dickstein, Systems Project Engineer with the General Electric (GE) Company's Missile and Space Division, explains that the concept of a general-purpose automated "spacetruck" for delivering "freight" grew from GE work to design a lander to transport a robot rover to the moon. Dickstein makes only a gross estimate of the spacetruck's weight (15,000 pounds) and no estimate of its size, stating that this can await determination of booster payload capacity and launch frequency, the amount of cargo needed on the moon, and other factors. He estimates, however, that cargo will make up about 23 percent of the total weight launched toward the moon; the disk-shaped cargo "platform" with sloped outer edge ("ramp"), landing gear, and vernier motor 12 percent of the total; and the "coarse retropropulsion" module, 59 percent. Shifting relative positions of the moon and the Earth launch site restrict deliveries to certain days of the month - however, daily delivery opportunities are desirable to spread out launches (reducing the number of Earth launch pads needed), allow emergency deliveries, and avoid a backlog of loaded spacetrucks on the lunar surface. This last increases the need for thermal and micrometeoroid shielding to protect parked cargoes, the weight of which must cut into payload capability. Dickstein opts for parking the spacetruck in low-Earth orbit (LEO) after launch from Earth to provide daily launch opportunities. A small set of solar cells on the cargo platform ramp provides electricity during flight. Landing and unloading occurs as follows:

  1. Midcourse correction using the coarse retropropulsion motor ensures that the spacetruck lands no farther than 10 miles from the intended target.

  2. Spacetruck orients for coarse retropropulsion using star tracker. 

  3. Liquid-propellant coarse retropropulsion motor ignites at 100 miles altitude (5 minutes before landing) and burns until its chemical propellants are exhausted at 10 miles altitude (3 minutes before landing). This removes 95 percent of total approach velocity. 

  4. With approach nearly vertical to the surface the coarse retropropulsion module is discarded. Steerable liquid propellant vernier engine fires to cancel residual horizontal motion. 

  5. Vernier engine completes touchdown. The design includes no provision for obstacle avoidance during final approach and landing - it counts on its broad base and low center of gravity to float in soft dust and straddle boulders and small craters without toppling. The spacetruck "impacts" on inflated bags or landing legs (the latter is Dickstein's preference) at 20 feet per second (about 14 miles per hour). 

  6. The surface crew reaches the space truck, disassembles thermal/meteoroid shielding, and removes the cargo, lowering it to the surface via the ramp.


	21. 1962:large launch vehicle planning

The Large Launch Vehicle Planning Group (LLVPG) was formally established on July 20, 1961. NASA's Nicholas Golovin chaired the group, which included seven representatives from NASA and seven from the Defense Department. The purpose of the Golovin Committee, as the LLVPG became known, was to assess U.S. national launch vehicle needs in light of President John F. Kennedy's goal of a man on the moon by the end of the 1960s. NASA Administrator James Webb and Defense Secretary Robert McNamara directed the committee to assume use of either an Earth-Orbit Rendezvous (EOR) or Direct Ascent moon landing plan. In EOR, multiple launch vehicles place moonship parts and propellants into LEO. After assembly, the moonship flies directly to the moon and lands, then lifts off and flies back to Earth. In Direct Ascent, the moonship lifts off from Earth on top of a large rocket and flies directly to the lunar surface, then lifts off and flies directly back to Earth. The Committee's report identifies four launch vehicle classes:

  * _Class I_ launch vehicles are Titan II and Titan III variants with solid-propellant strap-on rockets and Centaur, Atlas, and Agena upper stages. Payload capacity to low-Earth orbit (LEO) ranges from 1.5 to 14.1 tons. Class I rockets launch automated NASA and Defense Department payloads and Gemini piloted flights. 

  * _Class A_ rockets launch large piloted spacecraft such as Apollo, Dyna-Soar, and an Orbiting Laboratory into LEO. In mid-1961, Apollo was considered an Earth-orbital follow-on to Mercury with eventual circumlunar flight application. Class A rockets include the Saturn C-1 (10.9 tons to LEO) and Saturn C-1B (16.5 tons to LEO). 

  * _Class B_ rockets launch piloted circumlunar missions, and also piloted lunar orbital and landing missions using EOR and Lunar-Orbit Rendezvous (LOR) techniques. Circumlunar missions launch directly from Earth's surface, swing around the moon without entering orbit, and fall back to Earth. In LOR, a small lander detaches from its lunar-orbiting mothership, lands on the moon, then returns to the mothership. An LOR moonship could be assembled in LEO using EOR, or could be launched from Earth as a unit on a single Class B rocket. The Golovin Committee's charter did not mention LOR, but its members decided that the potentially weight-saving technique should be included in their deliberations because it could dramatically reduce 1960s launch vehicle requirements. Class B launch vehicles include the Saturn C-5, which could launch 112.5 tons into LEO and 43.4 tons toward the moon. 

  * Giant _Class C_ launch vehicles - generic name Nova - would be used for piloted Direct Ascent lunar landing missions. The committee's preferred Nova configuration, designated C-11, would launch 190.5 tons into LEO and 73 tons to the moon. The largest Nova configuration, C-20, would launch 254 tons into LEO and 101.5 tons to the moon.

The Golovin Committee report projects a total of 879 NASA and Defense Department missions before 1970, not including Class I missions. Defense Department missions use Class A rockets (a total of 523), while NASA needs 277 Class As, 69 Class Bs, and only 10 Class Cs. The report then makes wide-ranging recommendations. These include:

  * "A major engineering effort should be made to develop rendezvous operations techniques in both earth and lunar orbits as possible approaches for accomplishing the manned lunar landing mission at the earliest possible date. . ." because "[t]he Class B vehicle required for manned lunar landing by rendezvous operations will be available earlier than the Class C vehicle necessary to carry out the mission by [D]irect [A]scent." The report states that, if rendezvous in space is not a major hurdle, then "use of the Class B vehicle offers the earliest possibility of a manned lunar landing." It advises, however, that work should continue on Class C rockets "[s]ince it is by no means certain that the development of rendezvous operations will advance rapidly enough to provide earliest accomplishment of [a] manned lunar landing." 

  * "Develop as promptly as possible a Class B vehicle. . .consisting of a four or five F-1 engine first stage, a four or five J-2 engine second stage and a one J-2 engine third stage. . .This vehicle should be designed for use as a two-stage vehicle for [LEO] missions and a three-stage vehicle for escape [lunar] missions. . ." Class B rockets matching this description include the Saturn C-5. The report urges that the third stage, designated S-IVB, be developed as quickly as possible. It recommends replacing the S-IV stage on the Saturn C-1 with the larger S-IVB stage, thus creating the Saturn C-1B. This would allow early testing of the S-IVB stage so that it could then be re-applied as the Saturn C-5 third stage.


	22. 1962:lunar surface rendezvous

The authors, engineers from the Jet Propulsion Laboratory (JPL) in Pasadena, California, describe an enhanced version of the lunar surface rendezvous plan for landing a man on the moon outlined in the 1961 Lundin report. They state that their plan "offers several inherent advantages" over other moon mission plans - for example, "the moon. . .[serves] as a space station or assembly area [so] [w]eightlessness problems are avoided." It employs the following modules:

  * _Bus Module_: A four-legged lander based on automated Surveyor moon lander technology, it delivers all the plan's other modules to the moon. The Bus weighs 2476 pounds without propulsion or payload. It lifts off from Earth on a Saturn rocket with about 19,600 pounds of propellant on board and lands about 7600 pounds of payload on the lunar surface. The lunar surface rendezvous plan uses up to six Bus Modules. 

  * _Propulsion Module_: A 6130-pound solid-fueled rocket motor for lunar landing and liftoff. The plan uses up to 21 Propulsion Modules. 

  * The 5268-pound _Command Module_ is "derived from the Apollo Industry-Study Capsules" U.S. companies designed after NASA opened the Apollo program to bids in July 1960. The plan uses two Command Modules. 

  * The 1290-pound _Mission Module_ has as much habitable volume as a Command Module, doubling the living and working space available to the astronauts during the voyage from Earth to moon and on the lunar surface. The plan uses one Mission Module. 

These modules are combined to create the following vehicles:

  * The _Refueler_ consists of a Bus Module and three Propulsion Modules. A fourth Propulsion Module is carried as cargo. Each piloted mission requires three refuelers.
  * The _Earth-return vehicle_ consists of a Bus Module, three Propulsion Modules, and a Command Module. Each piloted mission requires one Earth-return vehicle.
  * The _Lunar landing vehicle_ consists of a Bus Module, three Propulsion Modules, a Command Module, and a Mission Module. Each piloted mission requires one lunar landing vehicle.

The lunar surface rendezvous mission occurs as follows:

  1. Automated Ranger hard-landers and Surveyor soft-landers scout out the proposed landing site. Ranger leaves Earth on an Atlas-Agena rocket. Surveyor launches on an Atlas-Centaur. 

  2. A Surveyor establishes a homing beacon and "visual monitoring capability" at the landing site. 

  3. The first Refueler leaves Earth on a Saturn rocket. Descent and landing occur as follows on this and all subsequent flights: 

    * As the spacecraft falls toward the lunar surface, its three Propulsion Modules ignite to slow descent.
    * Shortly before touchdown the Propulsion Modules exhaust their solid fuel and drop from the Bus, crashing some distance from the landing site.
    * The Bus completes soft-landing using small liquid-fueled rockets.

  4. Two more Refuelers land near the first. 

  5. The unmanned Earth-return spacecraft leaves Earth on a Saturn rocket and lands close to the Refuelers. 

  6. Each of the three Refuelers transfers its Propulsion Module cargo to the Earth-return vehicle. The JPL team proposes two possible transfer methods: 

    * _Above-the-surface transport_ "would use mechanisms such as an overhead extendable boom, or a cableway, along which a trolley travels carrying the [Propulsion Module]." This demands that the Bus perform a precision automated landing - the Earth-return vehicle must land no farther than 42 feet from each of the Refuelers.
    * _On-the-surface transport_ requires an additional Saturn launch, Bus lander, and three Propulsion Modules to deliver an automated transporter rover to the landing site. The rover moves to each Refueler in turn and picks up its Propulsion Module, then carries it to the Earth-return spacecraft.

The three Propulsion Modules delivered by the Refuelers replace the Propulsion Modules discarded by the Earth-return vehicle during descent.

  7. Controllers on Earth check out the Earth-return vehicle to make certain the Propulsion Modules are correctly attached. 

  8. If the Earth-return vehicle checks out "A-O.K.," three astronauts lift off from Earth in the lunar landing vehicle on a Saturn rocket. The lunar landing vehicle touches down automatically within walking distance of the Earth-return vehicle. The crew can take control during final approach if necessary. 

  9. The astronauts explore the lunar surface. 

  10. Exploration mission completed, the astronauts strap into the Earth-return vehicle and ignite the three Propulsion Modules to leave the moon. Nearing Earth, they discard the Bus and enter the atmosphere in the Command Module. 

The authors estimate program cost through the first piloted landing mission at only $2.5 billion, a figure which includes "the cost of the Ranger and Surveyor projects, launch vehicles, spacecraft, capsules, propellant, lunar complex, [and] TV monitoring of the mission."


	23. 1963:General Dynamics manned interplanetary mission studies

Krafft Ehricke, who led this study for GD, helped develop the V-2 missile for Nazi Germany. He came to the U.S. with Wernher Von Braun's rocket team in 1945. In 1953 Ehricke joined GD, where he was instrumental in Atlas missile development. In the late '50s he became involved in Mars expedition studies. Ehricke's team looks at piloted Venus and Mars "capture" (orbiter) missions. The Venus mission falls outside the scope of _Romance to Reality_. The 450-day Mars mission, set to occur in 1975, includes an optional piloted landing capability. GD's report describes modularized Mars ships traveling in "convoys" made up of at least one crew ship and two automated service ships. According to the report, "[t]he main difference between the two types of convoy vehicles is that the crew vehicle carries a life support system, and the [service vehicle] does not." Their systems "are standardized as much as practical" so the crew ship can cannibalize the service ships for replacement parts. At Earth-orbit departure the typical vehicle is arranged as follows (aft to fore):

  * The _M-1 engine system_ performs Maneuver-1 of the Mars expedition - escape from Earth orbit - hence its designation. The "booster," as it is known, includes one large or four small nuclear rocket engines, and from 400,000 to 1,400,000 pounds of liquid hydrogen propellant in a cluster of two 60-foot-diameter, two 25-foot-diameter, and two 33-foot-diameter tanks. In all the engine systems the smaller tanks are arranged around the larger tanks to reduce propellant loss in the event of a meteor strike. Loss of one tank means loss of from 5% to 15% of the propellant earmarked for a given maneuver. A damaged crew vehicle tank can be ejected and replaced by an identical tank from one of the service vehicles. 

  * The _M-2 engine system_ slows the ship at Mars so the planet's gravity can capture it into orbit (Maneuver-2). M-2 includes one nuclear rocket engine and 244,000 to 730,000 pounds of hydrogen propellant. Tankage consists of seven 14-foot-diameter tanks around one 20-foot-diameter tank or nine 14-foot-diameter tanks around one 30-foot-diameter tank. 

  * The _M-3 engine system_ launches the spacecraft out of Mars orbit toward Earth (Maneuver-3). M-3 includes one nuclear rocket engine and 138,000 to 275,000 pounds of hydrogen propellant in one 20-foot-tank surrounded by seven 14-foot-diameter tanks or one 30-foot-diameter tank surrounded by nine 14-foot-diameter tanks. 

  * The _M-4 engine system_ slows the ship at expedition's end (Maneuver-4). M-4 includes either one nuclear rocket engine or one chemical rocket engine. If nuclear, M-4 propellant is 11,800 to 21,400 pounds of hydrogen in one 20-foot-diameter tank. If chemical, M-4 propellant is 16,800 to 33,000 pounds of hydrogen/oxygen; the hydrogen is stored in a 14-foot-diameter tank and the oxygen in a 10-foot-diameter tank. 

  * The 10-foot-diameter, 75-foot-long _spine module_, or "neck," serves two structural functions - it places distance between the crew and the nuclear engines, thereby decreasing crew radiation exposure, and it places distance between the crew and the ship's center-of-gravity (CG). The GD team's preferred method of generating artificial gravity - tumbling the ship end over end around the CG - makes adequate crew/CG separation distance important (see number _1_ below). The spine also houses the electrical power system (SNAP-8 nuclear source or solar arrays). 

  * The crew ship includes the _Life Support Section (LSS)_, which houses the eight-person crew. GD proposes two standard LSS configurations - Dry and Wet. Both include a 10-foot diameter central section attached to front end of the spine module. This houses the Command Module, repair shop, radiation shelter, and food storage. Command Module radiation shielding in the Dry configuration consists of boron-filled polyethylene supplemented in the floor by tanks of drinking water. The ship's bridge doubles as the "blockhouse" from which the crew controls the service vehicles. Crewmembers sleep in the radiation shelter to reduce their overall radiation exposure. The Dry LSS includes two-level, 10-foot-diameter Mission ("extension") Modules clustered around the central section. Individual levels can be sealed off if penetrated by meteors or otherwise rendered uninhabitable. Entire Mission Modules may be discarded if the crew must reduce spacecraft mass to return to Earth - for example, if a large amount of propellant is lost and cannot be replaced from the service vehicles. In the Wet configuration, the M-4 hydrogen propellant tank surrounds the Command Module to provide radiation shielding. The central section repair shop protrudes from the front of the M-4 tank to provide attachment points for the four mission modules. Both configurations include two "taxis" docked to ports on the central section - see number _2_ below. 

  * On the service ship the _Service Module Section (SMS)_ replaces the LSS. Each service vehicle has a spine in case the crew vehicle propulsion section becomes damaged and must be replaced by the service vehicle propulsion section. The SMS is a hangar for auxiliary vehicles and scientific probes. See number _2_ below. 

  * _Earth Entry Module (EEM):_ Both the crew and services ships carry this auxiliary vehicle. See number _2_ below. 

  * The _M-5_ propulsion unit on the ship's nose spins the ship to create artificial gravity, de-spins it to permit maneuvers, and controls attitude. It carries 9500 pounds of propellant. Both the crew and services vehicles carry M-5, though the service vehicles do not spin.

Ehricke's team focuses on the following areas:

  1. _Artificial gravity:_ "It would be rather presumptious [_sic_] at this early date," the report states, "to make a decision whether gravity will be mandatory for crews during missions of long duration. . .If gravity is provided, the design of much of the equipment aboard is simplified because it can be built by long-adopted engineering practices where gas convection and liquid flow are natural." However, the only known means of producing artificial gravity - rotation - produces undesired effects. A person walking toward the center of a rotating system will tend to veer sideways; often they will become nauseated if they turn their head. The shorter the rotating system's radius and faster its rotation, the more pronounced these effects become. The report states that five rotations per minute is the approximate upper limit. The Ehricke team foresees tumbling the crew vehicle end over end about the ship's CG to create about 25% Earth gravity. As engine systems M-1, M-2, and M-3 are cast off, the crew ship grows progressively shorter. The ship's CG shifts forward - for example, CG before the M-1 maneuver is at the aft end of the M-2 system, 420 feet from the ship's nose; at the start of the M-2 maneuver it is located at the front of the M-2 engine system, 265 feet from the nose. This forces faster rotation to sustain the same gravity level. The report proposes joining the crew vehicle to the aft end of a service vehicle to shift CG away from the crew, permitting an acceptable rotation rate during return to Earth. Spinning the ship also makes sighting on stars difficult, interfering with celestial navigation. Ehricke's team points out that the non-spinning service vehicles can be used to assist navigation. 

  2. _Auxiliary vehicles & probes:_ According to Ehricke's team, "[a] large number of vehicles is involved in a manned planetary capture mission." Auxiliary vehicles include the _EEM_, a conical capsule carried in a housing on the front of the LSS and SMS. The crew reenters Earth's atmosphere in the EEM at expedition's end; it serves also as an emergency abort vehicle during the M-1 maneuver. The service vehicles each carry a spare EEM to provide a pressurized volume for visiting crewmembers and backup to the crew vehicle EEM. The _taxi_ is a "commuter between convoy vehicles. . ." and serves as "a 'tugboat' for conveying fuel tanks or bulky spare material between convoy vehicles." Each taxi weighs 1350 pounds fully fueled. The piloted Mars Excursion Vehicle (MEV) lander, if included, is carried in the SMS. The MEV can support two men for seven days on the martian surface. The SMS also carries most of the expedition's automated probes. These include the _Returner_Mars sample collector, which resembles the MEV; _Mars Lander_, based on Surveyor lunar soft-landing technology; _Deimos Probe (Deipro)_ and _Phobos Probe (Phopro)_ Mars moon hard landers based on Ranger lunar hard lander technology; _Mars Environmental Satellite (Marens)_ orbiter; and _Floater_ balloons. There are also two novel automated probes - the _Mapper_ travels to Mars attached to the crew ship and operates as a crew ship instrument in Mars orbit. It only detaches when the crew ship prepares to leave Mars orbit, becoming an independent satellite for beaming images back to Earth. The _Convoy Companion (C2)_ detaches from a service vehicle to perform "sensitive space physical experiments" free from interference en route between planets or at Mars. 

  3. _Launch vehicles & assembly:_ Ehricke's team favors replacing or augmenting the Saturn C-5 (as the Saturn V was known at this time) with a "Post Saturn" heavy lift rocket capable of placing 1 million pounds in Earth orbit - four times the C-5's capacity. Two Post Saturn launches could place an entire ship into orbit so only one rendezvous and docking would be required to complete assembly. By contrast, eight C-5 launches are needed to launch one ship's components, followed by seven rendezvous and docking maneuvers to complete assembly. Ehricke's team envisions using tethers, winches, small thrusters, and space taxis to push various spacecraft components into place. 

  4. _Crew complement:_ The eight-person crew consists of a 1) mechanical engineer who serves as Commander; 2) electrical engineer who serves as Deputy Commander; 3) engineer-physicist specializing in nuclear equipment; 4) engineer-astronomer and 5) engineer-physicist who share responsibility for communications, navigation, and the meteor radar; 6) physicist-geophysicist and 7) astronomer-geologist who share responsibility for onboard science instruments; and 8) physician-biologist who serves as Flight Surgeon. The crewmembers have rotating 12-hour duty shifts, in part because "a busy schedule is probably the most efficient antidote against psychological and morale problems. . ." The Ehricke team recommends table tennis as a form of in-flight exercise.

Ehricke's team includes a manned Mars capture mission development schedule. Highlights include:

  * _July 1965:_ Post Saturn launch vehicle receives "Full go-ahead." 
  * _May 1968-April 1970:_ Nuclear rocket engines tested in Nevada. 
  * _July 1968:_ Crew selection (three crews of eight men each, later reduced to Prime and Backup crews). 
  * _November 1968:_ First LSS module tested attached to Earth-orbiting space station. 
  * _June 1969:_ First of four Earth-orbital flight tests of the M-4 engine system. 
  * _First quarter 1971:_ LSS modules declared operational. 
  * _November 1972:_ Manned lunar landing test flight with MEV, Returner, and Lander. 
  * _March-April 1973:_ The prime and backup crews perform an interplanetary launch dress rehearsal in Earth orbit. 
  * _August 1973:_ Post Saturn launch vehicle declared operational. 
  * _November 1973-July 1974:_ The prime and backup crews conduct simulated flight operations aboard the crew vehicle in Earth orbit. 
  * _March 1975:_ Mission departure.


	24. 1963:Mars mission design studies

Hammock and Jackson, with NASA's Manned Spacecraft Center in Houston, call Mars "perhaps the most exciting target for space exploration following Apollo. . .because of the possibility of life on its surface and the ease with which men might be supported there." They say that "the most attractive [Mars mission] modes appear to be variations of three basic modes."

  * _Flyby-rendezvous mode:_ The Direct and Flyby spacecraft reach Earth orbit atop Saturn V rockets. The spacecraft each retain their last Earth-departure rocket stage for use as a counterweight to generate artificial gravity. The unmanned Flyby craft departs 50-to-100 days ahead of the manned Direct craft on a 200-day trip to Mars. The Direct craft, which includes the Mars Excursion Module (MEM) lander, reaches Mars ahead of the Flyby craft after a 120-day flight. The astronauts separate in the MEM and either land directly or brake aerodynamically (that is, use atmospheric drag to slow down) into Mars orbit before landing. Forty days later the Flyby craft passes Mars and begins the voyage back toward Earth. The crew lifts off in the MEM ascent vehicle and boards the Flyby craft two days after leaving Mars. Near Earth the astronauts separate from the Flyby spacecraft in an Earth-return capsule, enter Earth's atmosphere, and land. 

  * _Aerodynamic-braking mode:_ The spacecraft departs Earth orbit on a 120-day flight to Mars. To create artificial gravity the spacecraft divides into two parts linked by tethers and "extension arms" and rotates end over end. Near Mars the spacecraft despins and brings its separated components together to assume Mars aerodynamic-braking configuration. The Mars surface explorers separate the MEM from the orbiting mothership and land for a surface stay of 10 to 40 days. They then lift off in the MEM ascent stage, dock with the orbiting ship, and leave Mars orbit. Earth atmosphere reentry occurs as in the Flyby-rendezvous mode. 

  * The _propulsive-braking mode_ mission design resembles the aerodynamic-braking mode design, except that a propulsion stage decelerates the ship and places it in Mars orbit. Hammock and Jackson point out that this mode scores over aerodynamic-braking in that "[t]here are no requirements that the spacecraft have any heat protection or any special aerodynamic configuration. . .Therefore, freedom is allowed in the manner in which provisions will be made for packaging the MEM and for producing artificial gravity."

Hammock and Jackson find that the all-propulsive chemical-propellant spacecraft design masses the most at Earth-orbit launch (2.5 million pounds), while the aerodynamic-braking nuclear-propellant design is lightest (600,000 pounds). The flyby-rendezvous chemical and aerodynamic-braking chemical designs mass about the same (1 million pounds). The heaviest design requires six Saturn V launches.


	25. 1964:Boeing lunar base studies

It seemed reasonable in 1964 to expect that the Apollo transportation infrastructure established at great cost would continue to support a permanent American lunar presence after initial piloted landings in the 1967-1969 period. Lunar Exploration Systems for Apollo (LESA) was planned as an Apollo follow-on spanning 1970-74. In this Boeing study, LESA crews conduct

  * surface reconnaissance
  * geological and geophysical survey
  * economic geology research
  * astrophysical research
  * fuel manufacturing pilot plant operation

Saturn V rockets launch all base hardware from Earth. Crew transport is initially by modified Apollo spacecraft. The LESA base is designed for evolutionary growth, so spacecraft capable of transporting larger crews are assumed in later phases. The basic base module is a 25,000-pound, 2813-cubic-foot "shelter" with two chambers: an outer toroid with storage lockers, airlock, and hatch for linking to other shelters; and an inner cylinder with galley, bunks, and food and water storage. The shelter reaches the lunar surface atop a Lunar Logistics Vehicle (LLV) automated lander. The LESA program proceeds through four phases:

  * _Phase 1_: The first 3-man LESA crew lands near the phase 1 shelter in a modified Apollo Lunar Excursion Module (LEM). During a 3-month stay, the astronauts conduct traverses in a "basic rover" delivered in the unpressurized part of the shelter. Fuel cells and solar arrays provide power. 

  * _Phase 2_: A six-man crew lives for six months in the first base shelter or in a second shelter at another site. They stack lunar dirt on top of the shelter to serve as radiation shielding and upgrade the rover with an "extended mobility module." Nuclear power units and other equipment arrive on unmanned LLV landers. 

  * _Phase 3_: Another shelter module arrives, permitting 12-man crews. The base operates for 12 months or more. 

  * _Phase 4_: The final shelter arrives, permitting an eighteen-man base crew. The rover tows the shelter modules (temporarily fitted with wheels) together to link them in a line. The base operates for 24 months or longer.


	26. 1964:the Ford Aeronutronic MEM

NASA's Marshall Space Flight Center (MSFC) initiated the Early Manned Planetary Interplanetary Expeditions (EMPIRE) studies in 1962. The 1963-64 EMPIRE follow-ons, which were administered by NASA Headquarters, included other NASA centers eager to avoid being left out of planning NASA's possible future direction. These included NASA Ames Research Center and the Manned Spacecraft Center (MSC) in Houston, Texas. The present study, which was performed by Philco Aeronutronic between May and November 1963 under contract to MSC, is the first detailed piloted Mars lander design. Aeronutronic proposes a 10-year, $6.2-billion Mars Excursion Module (MEM) development program. A major problem faced by Mars lander designers at this time was the lack of good Mars atmosphere data. Aeronutronic notes that "two orders of magnitude variations in density at a given altitude were possible when comparing Mars atmosphere models of responsible investigators," then settles on a "nominal atmosphere" composed of 94 percent nitrogen, 2 percent carbon dioxide, and 4 percent argon with traces of oxygen and water vapor at roughly 10 percent of Earth sea-level pressure. Based on this atmosphere, Aeronutronic proposes a "modified half-cone" lifting body MEM with two winglets. (The design is unworkable in the actual martian atmosphere, which is made up almost entirely of carbon dioxide at about 1 percent of Earth sea-level pressure.) The 29-to-33.5-ton MEM measures about 30 feet long and 33 feet wide across its tail. The first Mars landing is targeted for the 1975-79 period, and occurs as follows:

  1. _MEM separation:_ Aeronutronic's MEM is designed for use with the aerobraking version of MSC's 1963 Mars expedition spacecraft. The spacecraft, which carries the MEM on its back under a thermal/meteoroid shield during the trip to Earth, enters a 550-kilometer-high circular Mars orbit and deploys "prelanding experimental probes" to the proposed MEM landing site. Two hours before de-orbit the crew casts off the thermal/meteoroid shield. The landing party, which consists of the captain/scientific aide, first officer/geologist, and second officer/biologist, dons space suits and enters the small flight cabin at the front of the MEM. Five minutes before de-orbit the MEM separates from its mothership and retreats to a distance of 1000 feet using 12 small thrusters attached to its flat aft end. There it points its tail forward and fires its single descent engine, which is of an advanced plug-nozzle design. 

  2. _Atmosphere entry and parachute deployment:_ The MEM enters Mars' atmosphere with its nose forward and tipped up. The MEM's heat-resistant hull is made of columbium with nickel-based alloy aft surfaces. Its nose reaches a maximum temperature of 3050 degrees Fahrenheit due to friction heating. About 75,000-100,000 feet above Mars, at a speed of Mach 1.5, the single parachute deploys and the MEM assumes a tail-down attitude. Abort to Mars orbit is possible until parachute deployment - if the parachute fails the spacecraft is falling too fast (1500 feet per second) for the ascent stage engine to slow it and boost it back to orbit. Abort can occur any time after successful parachute deployment, however. 

  3. _Landing:_ The plug-nozzle engine ignites a second time and the parachute separates. The MEM carries enough propellant for 60 seconds of maneuvering and hover prior to touchdown. The MEM sets down on four landing legs with crushable pads in a tail-down attitude.

Aeronutronic attempts to select a landing site using photographs taken by Earth-based telescopes. Theorizing that life forms might follow the retreating edge of the melting polar cap in springtime, they suggest targeting the MEM to a region called Cecropia at 65 degrees north latitude (this corresponds to Vastitas Borealis north of Antoniadi crater on modern Mars maps). Upon landing, the astronauts cast off panels covering the MEM windows and look out over their landing site to evaluate "local hazards" (this will, Aeronutronic states, include a "search for unfriendly life forms"). They then climb through a tunnel within the MEM leading between full ascent and empty descent propellant tanks to a living area in the bottom (tail) of the vehicle. Mars surface access is through a cylindrical airlock that lowers like an elevator from the living area. The astronauts set up a weather station and a 10-foot-diameter dish antenna for direct communication with Earth. Dixon states that "biological evaluation of life forms is essential for the first purely scientific effort to allow pre-contamination studies before man alters the Mars environment," implying that little effort will be made to prevent the astronauts from introducing terrestrial microorganisms. Aeronutronic lists "investigate life forms for possible nutritional value" among the tasks of the Mars biology study program. The crew explores Mars for between 10 and 40 days, spending about 16 man-hours outside the MEM each day.

Ascent occurs as follows:

  1. _Prepare site:_ The astronauts pack up equipment for possible re-use by a follow-on crew. The weather station and other equipment are left operating - these will survive ascent stage liftoff and continue radioing data to Earth for as long the MEM's fuel cells continue to generate electricity. 

  2. _Liftoff and ascent:_ The ascent stage motor fires and the flight cabin blasts free of the descent stage. Two propellant tanks are cast off during ascent. The ascent stage includes 14 attitude control thrusters. 

  3. _Intermediate orbit, rendezvous, and docking:_ The MEM ascent stage enters orbit below the orbiting mothership soon after ascent engine shutdown. The astronauts ignite the ascent stage engine twice more to match orbits with the mothership, then cast off the ascent engine. The attitude control system provides propulsion for rendezvous and docking. After docking and crew transfer the MEM ascent stage is discarded.


	27. 1964:the Apollo X study

The Apollo System Extension (ASE) program uses modified Apollo hardware to conduct longer and more complex lunar missions than possible using the baseline Apollo system. Two ASE missions occur in lunar orbit, while the third is a 14-day lunar surface expedition. This NASA MSC internal note proposes two approaches to the 14-day expedition:

  * _Approach one:_ Two astronauts pilot an Extended Lunar Excursion Module (LEM) resembling the baseline Apollo LEM to a pinpoint landing near a pre-landed LEM Truck. The Truck is a descent stage equipped with ascent stage systems required for automated landing; payload replaces the ascent stage. The Truck's 7000-pound payload includes 2887 pounds of water, food, lithium hydroxide canisters, and fuel cell reactants. Other possible Truck payloads include a shelter module or a large pressurized rover for long surface traverses. 

  * _Approach two_: A single second-generation LEM-II carries crew and expendables for the 14-day surface stay. System modifications include sturdier landing gear to support LEM-II's greater weight (2588 pounds heavier than the baseline LEM); enlarged expendables tankage; a combination fuel cell/solar cell power pack; and a space radiator for avionics cooling in place of the baseline LEM's water evaporator.


	28. 1965:Mars Voyager landing sites

Until the 1980s, most United States automated explorers bore names connoting ventures into unknown parts - Explorer, Pioneer, Ranger, Surveyor, Mariner, and Voyager. Most people today identify the last of these names with the spectacularly successful pair of outer planet flyby spacecraft launched in the late 1970s. There was, however, an earlier Voyager program. First announced in 1960 as a follow-on to the planned Mariner planetary flyby program, the original Voyager aimed to explore Venus and (especially) Mars using orbiters and landing capsules. For their study of possible Voyager Mars landing sites, Sagan, an assistant professor of astronomy at Harvard, and Swan, Senior Project Scientist at Avco Corporation, invoke a Voyager design study Avco performed in 1963 on contract to NASA Headquarters. The "split-payload" spacecraft, which launches from Earth on a Saturn IB rocket with an "S-VI" upper stage, consists of an orbiter "bus" and a landing capsule. The lander is sterilized before Earth launch to prevent biological contamination of Mars. Near Mars it separates from the orbiter, enters the martian atmosphere, and floats to the surface on a parachute. Upon landing it deploys and begins 180 days of operations. The orbiter, meanwhile, fires rockets to slow down and enter martian polar orbit, where it photographs the surface and serves as radio relay for the lander. Swan and Sagan note that their Voyager design has operational constraints that limit possible surface targets. These include:

  * _Earth-to-Mars trajectory:_ The path the spacecraft takes from Earth to Mars varies with launch opportunity. Launch opportunities occur about every two years. Some opportunities, for example, favor a landing in one martian hemisphere. Course-correction rocket firings en route to Mars affect Mars arrival time (and thus the spread of possible landing sites). 

  * _Lighting:_ The landing site must be sunlit during landing to permit photography during final descent, and the Sun must climb at least 10 degrees above the lander's horizon each day during subsequent surface operations so science instruments can operate properly. 

  * _Communications:_ Lander and orbiter must be in radio communication for at least five minutes after separating. Orbiter and Earth must rise at least 10 degrees above the horizon at the landing site to permit daily radio communication sessions. If the martian atmosphere is denser than 10 percent of Earth atmosphere density, the Orbiter must rise at least 30 degrees above the lander's horizon to avoid serious signal weakening (the precise density of the martian atmosphere was unknown at this time, but was consistently overestimated).

Operational constraints combine to create landing "footprints" that vary in extent depending on the Mars launch opportunity used. The footprint for the 1969 opportunity, for example, is a north-pointing wedge centered on 270 degrees longitude and spanning from 70 degrees south to 60 degrees north latitude. Sagan and Swan note that Avco's Voyager lander can be targeted to specific sites within these footprints, and propose that exobiologically interesting sites be given priority. Their analysis of what constitutes such a site is, of course, based exclusively on observations using Earth-based telescopes; no spacecraft had yet visited Mars when they published their paper. They cite the "wave of darkening" spreading from polar cap to equator in the springtime hemisphere, which is widely interpreted as a response by martian plants to moisture from the melting ice cap. Each wave terminates about 20 degrees beyond the equator from the pole where it started. That is, if the wave begins at the north pole, it terminates at about 20 degrees south latitude. They then propose possible landing sites for the four Mars launch opportunities spanning 1969-1975.

  1. _1969 opportunity (landing date - October 31, 1969):_ Two landers arrive during springtime in Mars' southern hemisphere, when the wave of darkening is near its peak, making it the best biological exploration opportunity until 1984. Sagan and Swan acknowledge, however, that it may occur too soon for Voyager to be ready. Top priority sites are northern hemisphere dark regions Solis Lacus and Syrtis Major ("[d]arkest of the Martian dark areas"), both of which lie within range of the southern hemisphere darkening wave and are relatively warm on the arrival date. Other candidate sites are Mare Sirenum, Lunae Palus ("dark area with greatest changes"), and Trivium Charontis ("striking anomalous color changes"). 

  2. _1971 opportunity (landing date - December 14, 1971):_ Swan and Sagan note that 1971 demands the least energy to reach Mars of any opportunity considered. They suggest two possible ways of taking advantage of this. Four landers (two per orbiter) could reach Mars as the southern hemisphere wave of darkening fades. Top priority sites for this approach are the southern polar cap, southern hemisphere dark areas Mare Cimmerium and Aurorae Sinus, and Lunae Palus in the north. Other candidates are Solis Lacus (if not explored in 1969 or if a second landing at a single site is desired) and Mare Serpentis. Alternately, the Voyager missions this year could use a higher-energy path to deliver two landers to Mars as the southern hemisphere darkening wave begins. "Thus," they write, "the exobiologically highly desirable characteristics of the 1969 arrival can be completely duplicated in the 1971 launch period." 

  3. _1973 opportunity (landing date - February 24, 1974):_ Two landers explore deserts and "the so-called canal features." The accessible landing sites are relatively cold on the arrival date. Top priority sites are Propontis ("region of typical Martian canal") and Elysium ("near circular anomalous bright region of 'pinkish' coloration") in the northern hemisphere. Other candidates are Hellas ("bright area of anomalous 'yellowish' coloration") in the southern hemisphere, and northern hemisphere features Nix Olympica ("suspected to be a plateau, because of tendency for cloud formation"), Ismenius Lacus, and Mare Acidalium ("[b]iologically implicated both by infrared spectroscopy and by polarimetry"). 

  4. _1975 opportunity (landing date - August 28, 1976):_ Sagan and Swan propose that two Voyager landers explore Mars in this opportunity. Top priority sites are the northern polar cap and Mare Cimmerium ("[p]eak of wave of darkening early in arrival window"). Other candidate sites are Nepenthes-Thoth ("site of unusual changes in the 1940's") and Mare Acidalium.

Swan and Sagan look briefly at the possibility of launching Voyager spacecraft on powerful Saturn V rocket, and find that "superior site selection could be performed" if it were used. In fact, their "preliminary calculations" show that "the landing footprints for all post-1971 opportunities may be made to superimpose on the [highly favorable] 1969 footprint. . .if the Saturn V is used."


	29. 1965:an early manned Mars mission?

According to Robert Sohn, head of the Technical Requirements Staff, TRW Space Technology Laboratories, "[a]n integrated, detailed plan for early manned flight to Mars can be prepared now - must be prepared now if the nation is to make efficient use of the manned space programs that precede planetary missions." He proposes a four-step plan, the final step of which closely resembles the Mars expedition he planned for NASA’s Ames Research Center in 1963-64:

  1. _Baseline Apollo:_ Apollo system development produces Command Module (CM) spacecraft, orbital rendezvous techniques, and Saturn V heavy-lift rocket. Sohn targets the first Saturn V launch for early 1967 and first lunar landing for late 1969. 

  2. _Apollo-based space station:_ Extended-duration Apollo CM, advanced life support, and an Apollo Orbiting Research Laboratory (AORL) mission module permit NASA to gain experience with year-long stays in Earth orbit. The three-man AORL fills the Saturn V launch shroud under the CM where the Lunar Module lander is housed for Apollo lunar expeditions. Sohn targets the AORL for mid-1970. 

  3. _Mission module-based space station:_ The Medium Orbiting Research Laboratory (MORL) is an enlarged mission module housing six to eight men. They ride into orbit in a CM lacking a Service Module on top of the Saturn V-launched MORL. 

  4. _Mars expedition:_ Four or five uprated Saturn Vs, each capable of placing 200 tons into Earth orbit, launch Mars ship parts. According to Sohn, aerodynamic braking in Mars' atmosphere reduces propulsion requirements, so that "the step to Mars does not necessitate post-Apollo propulsion systems or, in fact, any basic enhancement of space technology beyond Apollo," and argues that the Mars ship's "cone-cylinder-flare shape. . .permits an efficient combination of the aero-entry system and various functional systems." Fully assembled, the Mars spacecraft consists of an Apollo CM ("cone") on top, MORL-type mission module ("cylinder") in the middle, and a rocket stage ("flare") for "Mars depart" propulsion at the bottom. The ship, which relies for electricity on fuel cells and solar energy, leaves Earth orbit on a large "Earth depart" stage. The Earth and Mars depart stages burn high-density hydrogen-fluorine propellants. The two-man Mars Excursion Module (MEM) lander, which also uses hydrogen-fluorine propellant, is a smaller aerodynamic "cone-cylinder-flare" vehicle carried inside the Mars ship's Earth-return propulsion stage. It lowers to the martian surface on a parachute. The astronauts explore for up to 15 days. The spent Earth depart stage reels out on a tether to serve as a counterweight for spinning the ship to provide one-sixth of Earth's gravity (one lunar gravity) during the Mars trip. The spent Mars depart stage plays the same role during the flight home to Earth. At journey's end the crew abandons the Mars ship and enters Earth's atmosphere in the CM. Sohn also describes a Mars flyby craft launched on a single uprated Saturn V - it lacks the MEM and aerodynamic braking system, and has a smaller propulsion stage for course adjustments in place of the Mars depart stage. Sohn targets the Mars flybys for 1975 and 1978 and the first Mars landing for 1982.


	30. 1965:conjunction-class manned Mars mission studies

This report is the product of a nine-month study performed by Douglas Aircraft Company on contract to NASA Headquarters in Washington, D.C. Werner von Braun's 1950s Mars studies described conjunction-class expeditions, but in the 1960s most Mars expedition plans were opposition class. The names refer to the position of Mars relative to Earth about halfway through the mission - for the former, Mars moves behind the Sun as seen from Earth (that is, reaches conjunction) halfway through; for the latter, Mars is opposite the Sun in Earth's skies (that is, reaches opposition) about halfway through the expedition. Conjunction-class expeditions are typified by low-energy transfers to and from Mars, each lasting about 6 months, and long stays at Mars - roughly 500 days. Total expedition duration is about 1000 days. Opposition-class expeditions have one low-energy transfer and one high-energy transfer separated by a short stay at Mars - typically less than 30 days. Total duration is about 600 days. Because they require more energy, opposition-class expedition spacecraft require more propellant. All else being equal, a purely propulsive opposition-class Mars expedition can need more than 10 times as much propellant as a purely propulsive conjunction-class expedition, most or all of which needs to be lifted from Earth's surface using expensive heavy-lift rockets. Hence, the conjunction-class expedition plan is attractive; however, the long mission duration is problematical, for it demands great endurance and reliability from both machines and men, exposes the crew to risk from micrometeoroids and radiation for a longer period, and requires a more complex Mars surface program to enable productive use of the 500-day Mars stay. The Douglas report assumed the following "ground rules" in proposing its spacecraft design:

  * "propulsion was to be limited to chemical systems which would be available within the predicted state-of-the-art in the early 1970s" 

  * "aerodynamic braking maneuvers both at Mars and upon return to Earth were to be utilized to the fullest extent possible" 

  * "vehicle designs were not to be inhibited by current booster sizes, although the application of the Saturn V booster was to be examined"

The preferred vehicle design emerging from these ground rules is a 120.7-foot-long cone/cylinder made up of three basic parts. They are (aft to fore):

  * The cylindrical _Earth Departure Step (EDS)_, 54.7 feet in diameter and about 32 feet long, consists of a toroid (donut-shaped) hydrogen tank surrounding a spherical fluorine tank to which is attached a structure carrying four compact plug-nozzle rocket engines. These advanced engines lack the bells seen on most rocket engines. At expedition start the EDS pushes the Mars spacecraft out of Earth orbit on a low-energy path to Mars. 

  * The _Mars Orbit Module (MOM)_ is a truncated cone 39.7 feet long with a base diameter of 54.7 feet. It consists of a Mars Capture and Escape Propulsion (MCEP) section resembling the EDS in overall plan, but smaller, an Earth Entry Module (EEM), and a toroidal, two-level Life Support System (LSS) module weighing 89,620 pounds for the 10-person crew. The MCEP's four small plug-nozzle engines burn fluorine-hydrogen propellants. The EEM resembles the Apollo Command Module, but is larger (14 feet in length to Apollo's 10 feet) in keeping with the greater number of crew it must transport. The astronauts shelter in the 15,830-pound EEM during propulsive and aerobraking maneuvers and solar flares. To ward off radiation, the EEM is surrounded by a "water wall" 4.4 inches thick. The EEM nests in the hole of the LSS "donut," providing additional radiation shielding. The MOM is designed for weightless operations; however, the LSS includes a centrifuge to provide individual crewmembers with periodic exposure to acceleration, mimicking gravity exposure. The centrifuge consists of two cars mounted 180 degrees apart on a rail in a small toroid between the LSS levels. The MOM deploys from its aft end three 35-foot-diameter dish-shaped solar-dynamic arrays for generating electrical power. These shadow the MCEP system tanks from solar heating. A radio communication dish antenna also deploys. An airlock on top of the LSS contains hatches leading to the spacecraft exterior, the LSS, and the MEM. 

  * The conical _Mars Excursion Module (MEM)_ lander is home to six crewmembers during the 500-day stay at Mars. It measures 35.3 feet across its base and 49.8 feet tall. The 71-ton MEM consists of the MEM Landing Module (MLM), which includes extendible landing legs, a single plug-nozzle engine, Mars atmosphere entry heat shield, parachutes, and tanks holding fluorine/hydrogen propellants; the MEM Life Support Step (MLSS), a 7200-cubic-foot pressurized toroid for housing the surface crew; and the MEM Take-Off Module (MTOM), which includes the fluorine and hydrogen tanks and a plug-nozzle rocket engine for blasting the MEM Command Center (MCC) into Mars orbit at the end of the surface stay. The surface crew ride in the MCC during descent; in the event of trouble, they can abort by blasting free of the MLM/MLSS using the MTOM. The MCC, which contains at least one crew member at all times during the surface mission, is another toroidal compartment - it surrounds the MTOM fluorine tank and the hydrogen tank nests on top. The MLSS contains four levels. The lower level is storage; level two is exploration equipment storage; level three is the secondary control area and living/work space; and the top level contains sleeping quarters. Two 8700-pound radioisotope-powered rovers and a radioisotope surface power system are stored on level two. Heat shield material covers the MEM and MOM hulls. The MEM's heat shield is used twice - during Mars orbit entry and during descent to the surface.

Douglas points out that automated space probes must obtain data on the meteoroid environment in Mars space and the composition and density of Mars' atmosphere before final spacecraft designs can be developed. The company points out that "[a]s little as a 10% uncertainty in one term of the meteoroid flux equation causes a 35% change in the thickness of meteoroid protection at Mars and almost a 10% change in vehicle gross weight in Earth orbit" prior to launch. "Because of uncertainties in the martian atmosphere," the report states, "heat flux methods and heat shield material optimization is poorly developed." The Douglas conjunction-class expedition occurs as follows:

  1. _Earth-orbit assembly & departure:_ The Mars spacecraft diameter is too great to permit launch on a 33-foot-diameter Saturn V; it forms a "bulbous payload," Douglas states. Instead, the fully fueled MOM and MEM are launched on one 74-foot-diameter post-Saturn launcher capable of launching about one million pounds into Earth orbit. A second, similar vehicle launches the fully-fueled Earth Departure Step. The Earth Departure Step and MOM/MEM would be docked in Earth orbit. At the proper time the Earth Departure Step engines ignite, placing the MOM/MEM on a low-energy, approximately 200-day course to Mars. The Earth Departure Step separates and the solar-dynamic power system and radio dishes deploy. 

  2. _Mars arrival:_ The MOM/MEM perform a "skipping aerodynamic-braking maneuver" in Mars' atmosphere in a nose-forward attitude to slow down and enter elliptical Mars orbit. The Mars Capture and Escape section engines then ignite to place the spacecraft in a 500-mile circular Mars orbit. 

  3. _Mars landing & surface mission:_ After initial orbital reconnaissance, the surface crew enters the MCC and separates the MEM from the MOM. They fire the MLM engine to slow down, and enter Mars' atmosphere nose forward. Parachutes in the nose deploy to further slow then MEM, then the MLM engine ignites for final hover and landing. The crew reach the martian surface using a cylindrical airlock that extends down to the surface from the MLSS. They deploy the radioisotope system on Mars. Douglas states that the surface science payload and biology focus are the same as proposed in the 1963 Philco Aeronutronic MEM study. The rovers can transport three men on two-week traverses ranging up to 300 miles from the MEM. 

  4. _Mars liftoff & Mars departure:_ The MTOM engine ignites, launching the MCC into orbit. The MCC performs rendezvous and nuzzles its side up against the side of the MOM to lock its docking port to the airlock. The surface crew rejoins the orbital crew and transfers to the MOM the science payload (such as Mars samples), which can weigh up to 1580 pounds. The MEM is cast off, then the MCEP section fires its engines, ending the MOM's 500-day stay at Mars and placing it on course for Earth. 

  5. _Earth arrival:_ The crew enters the EEM and separates from the MOM. The EEM enters Earth's atmosphere, deploys parachutes, and makes a land landing. The MOM flies past Earth into solar orbit.

Douglas reaches a number of significant conclusions specifically related to long Mars stays, including:

  * "The space suit life support system being developed for early missions is not satisfactory for application to missions of very long duration. . .The major factor is the 8 lb. of water that is evaporated by the thermoconditioning system for each 3.5 hours of use." This can, Douglas estimates, cause a 15% increase in mass at Earth-orbit launch. Suits should also be made less cumbersome and use a nitrogen/oxygen air mix. 

  * Communications between the MEM, MOM, and Earth will not be constant throughout the long stay at Mars. Communication between Mars orbit and Earth is possible from 65% to 100% of the time; communication between Mars' surface and Earth is possible from 20% to 100% of the time. Communication between the MEM on the surface and the MOM in orbit is possible for about 2 hours each day in 15 minute increments. The report suggests Mars-orbiting and Sun-orbiting relays to permit more complete coverage.

Douglas proposes a 15-year development program for the conjunction-class mission. Sixteen vehicles are built, of which six are flight articles. Total program cost over 15 years is $17.5 billion.


	31. 1965:Gemini to the Moon

Gemini, NASAís second piloted space program, was originally named "Mercury Mark II." The program served as an experience-building bridge between the "man in a can" Mercury flights and Apollo lunar landing missions. Gemini stretched human staytime in space to the two weeks needed for a lunar expedition and let astronauts practice the rendezvous and docking maneuvers critical for the Apollo Lunar Orbit Rendezvous mission mode. Gemini missions occurred in low-Earth orbit (LEO). Throughout the 1961-66 period, however, some (notably astronaut Charles "Pete" Conrad) proposed taking Gemini higher. The present study, performed "in collaboration with NASA Manned Space Flight Center" (_sic_) in Houston, proposes a two-launch circumlunar Gemini flight between April and June 1967 to "enhance and complement the Apollo program with space 'firsts' of sufficient significance to greatly improve our national prestige." The circumlunar "Gemini spectacular" occurs as follows:

  1. _Titan III-C rocket liftoff_ \- The 140.6-foot-tall rocket places a modified Titan III-C transtage into 100-mile-high LEO. Titan III-C consists of two strap-on solid rocket motors (Stage 0), a liquid-fueled core (Stage I), a liquid-fueled stage II, and a liquid-fueled standard transtage (transtage 1). The modified transtage (transtage 2) reaches orbit riding on top of the standard transtage. Transtage 2 modifications include removal of systems to reduce weight and addition of a Gemini docking cone. 

  2. _Gemini liftoff_ \- The two-man Gemini, which consists of capsule, retro, and adapter sections, lifts off four minutes after the Titan III-C. A back-up Gemini launch opportunity occurs 90 minutes later when transtage 2 flies over Cape Canaveral at the end of its first orbit. The study notes that transtage 2 has a 7.5-hour usable lifetime in LEO, so the mission cannot occur if the second Gemini launch opportunity is missed. The report states that Martin Marietta is examining transtage 2 modifications permitting a 30-day wait in LEO. 

  3. _Gemini docks with transtage 2_ \- Rendezvous occurs 90 minutes after Gemini launch, at the end of Geminiís first orbit, and docking occurs within three hours of Gemini launch. The astronauts insert their spacecraftís nose into transtage 2ís docking cone. According to the study, the "interface between the Gemini capsule and transtage 2 is designed for utmost simplicity." The standard Gemini docking umbilical and other spacecraft systems are only lightly modified for this mission; for example, rather than create a new transtage 2 status display panel in the Gemini cockpit, a panel which can be viewed through Gemini's twin windows is added to the transtage 2 docking cone. The Gemini/transtage 2 combination is 36 feet, 8 inches long. 

  4. _Translunar injection (TLI)_ occurs about six hours after Gemini launch. The astronauts feel 0.6 Earth gravities of acceleration at transtage 2 ignition. They must be certain to secure their seat straps - because they face the front of transtage 2, acceleration pushes them out of their seats. During acceleration they feel as though they are falling toward Geminiís nose. Transtage 2 burns for 6 minutes, 40 seconds. As transtage 2 depletes its propellants it becomes lighter. Acceleration thus increases, topping out at five times Earth's gravity at transtage 2 shutdown. 

  5. _Gemini separation & circumlunar flight_ \- The astronauts back away from transtage 2 and turn their spacecraft in the direction of flight. Midcourse corrections using the standard Gemini propulsion system occur between three and 10 hours after TLI and when circumlunar Gemini is 40,000 miles out from the moon. The Gemini spacecraft passes behind the moon 82 hours after TLI. The mission is timed so the moon is in last-quarter phase as viewed from Earth - this means that half of the lunar far side is lit by the Sun, making it visible as the astronauts fly over. Additional midcourse maneuvers occur 40,000 miles after leaving the moon and between 5 and 10 hours before Earth atmosphere reentry. 

  6. _Gemini reentry_ \- The Gemini capsule casts off its adapter and retro sections, revealing a heatshield modified to withstand circumlunar return speed (36,000 feet per second). Total flight time in April-June 1967 is 143 hours for a splashdown in the Atlantic off Cape Canaveral.


	32. 1965:NASA lunar mission studies

Apollo planners focused the majority of their efforts on reaching Kennedy's politically motivated goal of an American man on the moon by 1970. However, as they became aware of the interests of the science community, many made efforts to accommodate scientific exploration in the Apollo program. The 1965 Lunar Exploration and Science Conference was held under auspices of the NASA-appointed Manned Space Science Coordinating Committee, which consisted of seven Working Groups. These covered Geodesy/Cartography, Geology, Geophysics, Bioscience, Geochemistry, Particles and Fields, and Lunar Atmospheres. In his foreword to this report, Richard Allenby, Deputy Director of NASA Manned Space Science Programs and coordinator for this conference, states that "[t]he function of the Working Groups and the Coordinating Committee is to advise NASA on a sound, feasible, scientific exploration program for the Moon." He adds that "this report represents the opinions and conclusions of the Working Groups and does not constitute official NASA policy" though "NASA plans to make every effort to implement those parts of the recommended program which appear feasible within available resources." In 1965 NASA's resources seemed considerable - the agency enjoyed a budget ten times larger than at its establishment in 1958, and had yet to confront the budget cuts that began in the 1967 fiscal year and the crisis in credibility spawned by the Apollo 1 fire. The report's recommendations "are limited to the 10-year period following the first Apollo lunar landings because a decade seems to be the approximate maximum time for which developments can be meaningfully forecast," and are divided into five mission types:

  * _Apollo_ missions "with durations limited to a day or two and with exploration limited to an area close to the point of landing. . ." Scientific experiments should "conserve the astronauts' time, the most valuable scientific commodity on the early missions." These missions would occur between 1967 and 1969. First priority is "to return the greatest number and variety of samples," and second priority is to emplace Lunar Surface Experiment Packages (LSEPs) which continue to return data after the astronauts depart. 

  * _Lunar Orbiter_ missions include the automated Lunar Orbiter program for mapping Apollo landing sites. Apollo Lunar Orbiter missions, the report recommends, should include "simple diagnostic experiments to be conducted in the orbiting Command/Service Module (CSM) in conjunction with Apollo experiments on the lunar surface." 

  * _Apollo Extension System-Manned Lunar Orbiter (AES-MLO)_: The report envisions five or six CSM lunar orbiters equipped with remote sensing packages. 

  * _Apollo Extension System-Manned Lunar Surface (AES-MLS)_: Five or six of these 14-day missions occur between 1969 and 1974. They include Local Scientific Survey Module (LSSM) rover traverses up to 15 kilometers from the landing site. The LSSM can carry 600 kilograms of equipment, including a drill for collecting 3-meter cores. The crew uses one-man Lunar Flying Vehicles. Each mission delivers to the moon several LSEPs and returns to Earth up to 300 kilograms of lunar samples. The report states that longer stays will allow more samples to be collected than can be returned to Earth, and calls for analysis equipment to be included to aid the astronauts in selecting the best samples for return. Most AES-MLS missions require two Saturn V launches. 

  * _Post-AES_ missions begin in 1975 and occur once per year until 1980. They include three-man, 800-kilometer traverses of the equatorial region lasting up to two months. Post-AES flights also include a Lunar Base permitting stays of up to a year. Lunar Base activities will include drilling to a depth of more than 300 meters and constructing and staffing large radio telescopes.


	33. 1965:the next 20 years of interplanetary exploration

NASA's Marshall Space Flight Center (MSFC) in Huntsville, Alabama, began as the U.S. Army's Redstone Arsenal. In the 1950s, German rocket engineers led by Wernher von Braun developed some of the earliest U.S. missiles at Redstone Arsenal, including the intermediate-range Redstone missile. The Redstone was the "Americanized" version of the A-4/V-2 missile Von Braun & Co. designed for Nazi Germany. A Redstone variant called Jupiter-C launched the first U.S. satellite, Explorer 1, on January 31, 1958. Just as Saturn was next after Jupiter among the planets, the Saturn series of rockets was next after Jupiter-C. In fact, Saturn I and Saturn IB used a cluster of Redstone tanks in their first stages. The Saturn series reached its apex in the Saturn V heavy-lift rocket of the Apollo moon program. Saturn V was the most powerful rocket in history. In this article, Wernher von Braun, at this time MSFC director, describes four manned spaceflight missions possible before 1985 using only Saturn-Apollo and planned nuclear rocket technology. They are

  * manned Venus flyby
  * manned Mars flyby
  * manned Mars landing
  * semi-permanent manned outpost on Mars

According to Von Braun, the Kennedy Space Center Complex 39 launch facilities built for Apollo can support these expeditions with few changes. Von Braun proposes assembling a Orbital Launch Facility modular space station for orbital checkout and fueling of interplanetary craft. For the 1978 Mars flyby, Von Braun introduces the MLV-3 booster, a "stretched" Saturn V capable of placing 310,000 pounds of payload into orbit - 90,000 pounds more than the Apollo Saturn V. The first MLV-3 places into orbit the flyby spacecraft and propellant module, which together weigh 275,000 pounds. The second delivers a Standard Propulsion Module (SPM) with a Nerva II nuclear rocket engine. The 8-man Mars landing mission (1982) requires ten MLV-3 flights to place 2,627,000 pounds of components into Earth orbit, including five SPMs (three for Earth orbit escape and one each for Mars orbit insertion and Mars orbit escape), Mars ship, lifting body Mars lander, and an Apollo Command Module for Earth atmosphere reentry. Four of the astronauts spend 20 days on Mars. The interplanetary spacecraft used to establish the semi-permanent Mars surface base (1984-1986) is a one-way vehicle. A dozen men live for 18 months in a "little village" of four cargo landers and two crew landers. Four landers and up to four extra crewmembers replace Earth-return propulsion and other hardware, so a relief expedition must be sent out to recover the explorers at the end of their long stay on Mars.


	34. 1966:manned Mars surface operations

The present paper summarizes a 1965 study conducted by Wilmington, Massachusetts-based Avco/RAD Corporation for the Advanced Systems Office at NASA's Marshall Space Flight Center in Huntsville, Alabama. The authors note that designing experiments for Mars exploration is made difficult by two factors:

  * On Earth, explorers can start with simple scientific investigations at an exploration site, return to their labs and offices, develop theories based on their data, then return to the exploration site prepared to conduct more complex investigations based on those theories. Interplanetary flight is so costly and time-consuming that this approach is impractical. The authors note, however, that Mariner and Voyager automated probes can conduct simple investigations prior to the first piloted mission. 

  * Humans will almost certainly "be surprised in some instance when we get to Mars or any other planet." The authors recommend that planners provide "the flexibility necessary to gather not only enough information, but variable amounts of different kinds of information over sufficiently wide dynamic ranges." The unexpected will then "have some probability of being caught in the net of observations."

Avco/RAD divides Mars into "concentric spherical zones," ranging from the endosphere (the deep, molten interior) to the gravisphere (near-Mars space, including dust belts and moons). Each zone demands different investigations. Endosphere and lithosphere (crust) investigations would, for example, include field geology, geodesy, radar mapping, subsurface heat flow, and seismometry. The paper notes that Mariner IV, which flew past Mars in July 1965, provided the first data on the martian atmosphere and electro/magnetosphere (magnetic field). It then describes two kinds of Mars expeditions.

  * The _minimal expedition_ uses Apollo (c. 1970) state-of-the-art technology, and includes six men, four of whom explore Mars' surface for 21 days while two remain in the command module orbiting Mars. The expedition carries 4600 pounds of science equipment and includes three surface modules: a shelter, a pressurized garage, and a two-man, 8700-pound mobile laboratory (molab) with 500-miles range. Astronauts wear coated-fabric space suits capable of supporting four-hour Marswalks. The first minimal expedition will, the authors anticipate, focus on exobiology, planetology, and finding resources for use by the follow-on synodic expedition. The minimal expedition lands at a site where the spring/summer "wave of darkening" is underway. (Until the late 1960s, this phenomenon, visible through Earth-based telescopes, was widely interpreted as evidence of seasonal plant growth on Mars.) A 1978 minimal expedition, for example, spends 21 days in Syrtis Major ("one of the darkest of martian dark regions") at the start of northern hemisphere summer. A 21-day minimal expedition will not show conclusively that Mars lacks microorganisms harmful to humans, the report states, "since incubation periods for interaction with alien life forms obviously cannot be determined without time consuming tests." The authors note that, even with a "very active schedule," the 21-day surface stay is too short to permit the astronauts to analyze the data they collect and modify the pre-planned experiment program to take into account their new discoveries. 

  * The _synodic (extended) expedition_ features three separate 14-man Mars surface bases using 1980s technology. Four men remain in Mars orbit, bringing the total expedition complement to 46 men. Surface stay time is 300 days. Each base includes 17,000 pounds of science equipment and eight surface modules: two seven-man shelters, two nuclear power plants, one pressurized garage, one unpressurized garage, and a pair of two-man molabs capable of 30-day, 1500-mile traverses. The three bases are "so situated as to provide access to all major features of interest." Northern Syrtis Major Base supports traverses to Libya and Aeria ("two northern desert regions"), while a base in Hellas ("unusually bright and somewhat anomalously colored desert region") provides access to Zea Lacus, where five canals intersect. The third base is situated among the south pole's snowy Mitchel Mountains. The large amount of crew and equipment, coupled with the long staytime, means that "time will be available to evaluate the progress of the experimental program, to formulate and test hypotheses[,] and to repeat critical experiments rather than to simply provide an immense amount of raw data for return to Earth."


	35. 1966:lunar base studies

This article was published in a special double issue of the journal _Astronautica Acta_ devoted to lunar bases. The issue represents the best lunar base thinking of NASA and contractor experts on the eve of budget cuts which, over 5 years, truncated the Apollo program and postponed lunar bases until the 21st century. Culbertson, director of the Advanced Manned Lunar Mission Studies Office at NASA Headquarters, presents a build-up sequence for the LESA lunar base described in the 1964 Boeing LESA study ([see](https://web.archive.org/web/20020325234403/http://members.aol.com/dsfportree/ex64a.htm)). The sequence assumes four Saturn V launches per year.

  * Month 1 - first basic shelter module lands unmanned
  * Month 4 - first 3-man crew lands at shelter
  * Month 7 - base deactivated, first crew departs
  * Month 13 - supply/mobility payload touches down near shelter
  * Month 15 - fuel module lands
  * Month 17 - second 3-man crew arrives and activates base
  * Month 19 - third 3-man crew arrives; base population six
  * Month 23 - second crew leaves
  * Month 25 - third crew deactivates base and departs
  * Months 28-35 - nuclear power module, second shelter, second supply module, and second fuel module each land unmanned
  * Months 37-43 - four 3-man crews land separately, bringing base population to 12

Culbertson describes several ways of delivering astronauts to the base using the Apollo Command and Service Module (CSM) and Lunar Module (LM). In each, the LM lands three crewmen, then remains dormant on the surface until called upon to ferry them back to lunar orbit. Three options exist for adapting the CSM to the lunar base program:

  * Single astronaut remains alone in lunar orbit for up to 6 months aboard a 4-man CSM while the 3-man base crew is on the lunar surface. 

  * Single astronaut returns in the CSM to Earth after dropping off the 3-man base crew. The CSM delivering the second base crew returns the first base crew to Earth. 

  * A three-man CSM operates unmanned in lunar orbit while the crew is at the base. Culbertson considers this option most attractive.

Apollo hardware is usable until base population surpasses 12, then a new direct ascent crew lander becomes more cost effective. In direct ascent mode, the crew lifts off from Earth inside a lander atop a Saturn V rocket and flies directly to the lunar surface. Lunar surface mobility systems include 1- and 2-man flying units and an electric rover powered by fuel cells or a nuclear isotope generator. Astronauts use the rover for 700-kilometer traverses lasting up to 4 weeks. The flying units can reach places inaccessible by rover and allow rapid return to base if the rover becomes stranded.


	36. 1966:lunar applications of a spent S-IVB

The Saturn V rocket used for Apollo moon landings weighed about 3000 tons at launch and included three chemical-propellant rocket stages:

  1. The 33-foot-diameter _S-IC first stage_ carried 4.6 million pounds of kerosene fuel and liquid oxygen oxidizer for its five F-1 rocket engines. They consumed 15 tons of propellants a second to develop a total of 7.5 million pounds of thrust at liftoff. The S-IC depleted its propellants in two and a half minutes at an altitude of 35 miles and fell into the Atlantic about 45 miles from its Cape Kennedy launch pad. 

  2. The 33-foot-diameter _S-II second stage_ carried 930,000 pounds of liquid hydrogen fuel and liquid oxygen oxidizer for its five J-2 engines, which developed a total of 1 million pounds of thrust. The S-II depleted its propellants after six and a half minutes at an altitude of 100 miles. 

  3. The 22-foot-diameter _S-IVB third stage_, manufactured by Douglas Aircraft Company, carried 230,000 pounds of liquid hydrogen and liquid oxygen for its single J-2. The S-IVB fired for two minutes to place the Apollo Command and Service Module (CSM) and Lunar Module (LM) spacecraft into 115-mile-high parking orbit. Stacked between the S-IVB and the Apollo spacecraft was the Saturn V's "electronic brain," the ring-shaped Instrument Unit (IU), manufactured by IBM. After checkout, the S-IVB fired again for five minutes to place itself, the IU, and the Apollo spacecraft on course for the moon. Following LM and CSM separation, the S-IVB vented leftover propellants and used auxiliary rocket engines to change course slightly so that it would not interfere with the Apollo expedition.

Beginning with Apollo 13 (April 1970), the S-IVB maneuvered after LM and CSM separation to crash on the moon. This was part of a lunar geophysics experiment - the impact registered on seismometers left behind on the moon by previous Apollo expeditions. From November 1965 to July 1966, Douglas studied making the S-IVB even more useful to lunar exploration by soft-landing it on the moon. The study grew from a NASA Marshall Space Flight Center proposal to reuse a spent S-IVB as an Earth-orbital space station, perhaps by 1968. According to this joint Douglas/IBM presentation, "[t]he voluminous interior of the S-IVB hydrogen tank can provide considerable living and working space on the lunar surface, much as it will in earth orbit. . .This sustained exploitation of basic elements of the S-IVB provides a considerable economic advantage over the development of new systems." The study examines five possible LASS S-IVB configurations before settling on one which lands the stage tail-down on four landing legs. Using the Douglas/IBM study's preferred design, the LASS S-IVB mission occurs as follows:

  1. _Launch:_ S-IC and S-II operations occur as described above. The landing legs unfold at the LASS S-IVB’s base just before S-II separation, then the J-2 engine fires to push the S-IVB on direct course for the moon (that is, the stage does not loiter in Earth orbit for checkout). At ignition the S-IVB weighs about 150 tons. The LASS S-IVB includes two steerable, throttleable RL-10 rocket engines on either side of the J-2 which also fire at this time. 

  2. _Translunar Coast_ lasts 110 hours. Flight controllers on Earth point the LASS S-IVB’s landing legs and J-2 and RL-10 engines toward the Sun. This warms the liquid oxygen stored in the lower part of the stage, preventing freezing, while at the same time placing the liquid hydrogen in the upper part of the S-IVB in shadow so that it does not boil and escape. Between 10 and 20 hours after launch the S-IVB re-orients itself to perform a course correction rocket burn using the RL-10 engines, then turns its tail toward the Sun again. If necessary, a second mid-course correction occurs 60-100 hours after launch. 

  3. _Landing:_ "Terminal operations" commence when the LASS S-IVB is 15,000 nautical miles from the moon. The stage turns its landing legs toward the moon under guidance from the IU. "Phase I Retro Braking" begins at an altitude of 60 nautical miles. The twin RL-10s fire at full throttle along with the J-2 engine to slow the S-IVB's fall and steer it toward a pre-landed radio beacon. At 25,000 feet the J-2 shuts down and "Phase II Vernier Descent" begins. The RL-10s throttle off 10 feet above the surface and the LASS S-IVB comes to rest near the beacon. Landed weight is about 30 tons, of which nearly 14 tons is cargo.

Astronauts can then land near the LASS S-IVB and put it to use. One configuration (see image below) includes a shelter on top with a hatch leading down into the hydrogen tank. Flooring and equipment stored in the shelter are lowered into the tank and deployed to make it habitable while a rover and other equipment are lowered to the surface. This configuration will support two astronauts on the moon for more than 14 days, the Douglas/IBM study finds. Alternately an LASS S-IVB can be tipped on its side for conversion into a long single-story habitat. A cluster of LASS S-IVBs, some upright and some on their sides, can be linked using pressurized passageways to form a modular lunar base. The Douglas/IBM study estimates that the first LASS S-IVB could land on the moon in 1970-1971.


	37. 1966:manned planetary mission studies

In April 1966, at the request of Charles Townes, chair of the NASA Science and Technology Advisory Committee (and Nobel Laureate), NASA Associate Administrator for Manned Space Flight George Mueller launched a piloted Mars flyby study within the Office of Manned Space Flight (OMSF) Planetary Joint Action Group (JAG). NASA applied at least as much study money in the 1960s to manned Mars flybys as to manned Mars landings. The JAG report (labeled "For Internal Use Only") places flyby missions within an evolutionary "integrated program" with "balanced" use of humans and robots, the objective of which is "maximum return at minimum cost, assuming intensive investigation of the planets is a goal." The program includes:

  1. _Apollo Applications Project (1968-73)_: Astronauts remain aloft in space stations based on Apollo hardware for progressively longer periods - some live in Earth orbit for more than a year to provide data on weightlessness exposure for a period approaching the duration of a manned Mars flyby mission. 

  2. _Mariner (1969-73) and Voyager (1973)_: A Mariner automated probe flies by Mars in 1969, followed by a Mariner Mars atmosphere probe in 1971. The first Voyager probe lands on Mars in 1973 bearing a suite of life detection experiments. Data from these probes aid manned flyby hardware designers. (Mariner 4 flew past Mars in July 1965. NASA adopted the promising Voyager series of robot explorers as a new project in 1964 with the aim of a 1971 Mars landing. In 1965, the landing was bumped to 1973 by funding cuts and a redesign prompted by Mariner 4 atmosphere data.) 

  3. _Manned Mars/Venus Flybys (1975-80)_: A manned Mars flyby mission leaves Earth orbit in September 1975. Mars flyby launch opportunities also occur in October 1977 and November 1979. Venus opportunities occur in June 1975, January 1977, August 1978, and April 1980. Multiple flyby missions are possible - a Venus/Mars mission can start in December 1978, and a Venus/Mars/Venus mission can launch in February 1977. 

  4. _Manned Mars Landing and Manned Venus Capture missions (1980-)_ see introduction of nuclear propulsion, a technology the JAG deems "essential for a flexible Mars landing program." (The main focus of the JAG was on Mars landings. The JAG was formed in 1965 in part at the urging of the Atomic Energy Commission, which sought aid in finding justifications for nuclear rocket development.)

The manned Mars flyby mission uses the following major spaceflight systems:

  * _Improved Saturn V heavy-lift rocket_: The basic Saturn V has a 138-foot-long S-IC first stage and a 81.5-foot-long S-II second stage. The Improved Saturn V includes modified F-1 first stage engines, a 158-foot-long MS-IC first stage for increased propellant capacity, and a strengthened S-II second stage. 

  * _MS-IVB rocket stage_: The Apollo Saturn V has a third stage, the S-IVB, which places the Apollo spacecraft into Earth orbit then restarts to push it toward the moon. MS-IVB features stretched tanks to increase propellant capacity. Added internal foam insulation permits it to remain in Earth orbit for 50-60 hours before solar heating causes its cryogenic (super cold) liquid hydrogen/liquid oxygen propellants to vaporize and escape. 

  * The _Flyby Spacecraft_ consists of (fore to aft): 

    * _Mid-Course Propulsion Module (MCPM)_ with four main engines. 

    * _Earth Entry Module (EEM)_ based on the Apollo Command Module for Earth atmosphere reentry at mission's end. The EEM can withstand the friction heat generated by reentry at 50,000 feet per second (that is, 15,000 feet per second faster than Apollo lunar return). The EEM serves double duty as a solar flare radiation shelter. MCPM propellant tanks around the EEM's upper portion provide added radiation shielding. 

    * The _Mission Module (MM)_ contains 2769 cubic feet of living space. The forward level, with walls lined by lockers containing freeze-dried foods, is for "rest and privacy." The aft level contains the flyby craft's operations console, science equipment, and wardroom table. The JAG proposes that MM structure and systems - such as life support - be based on a space station module design. 

    * The _Experiment Module (EM)_ includes unmanned probes; a probe deployment manipulator arm; biological laboratory; and a 40-inch astronomical telescope. In addition, the EM includes the airlock; a 19-foot-diameter radio communications dish antenna; and a 2000-square-foot solar panel capable of producing 22 kilowatts of electricity at Earth, 8.5 kilowatts at Mars, and 4.5 kilowatts at aphelion (farthest point from the Sun in the flyby craft's orbit - 2.2 times the Earth-Sun distance).

  * _Unmanned probes_ based on Mariner and Voyager technology. Probe compliment varies according to mission objectives. The 1975 mission includes three 100-pound Mars impactors, one 10,130-pound Mars polar orbiter, one 1290-pound Mars lander, and one 11,692-pound Mars Surface Sample Return (MSSR) lander. MSSR carries a three-stage liquid-fueled ascent vehicle for transporting a two-pound sample of Mars dirt and rocks to the flyby craft.

The 1975 flyby mission occurs as follows (apart from dates and probe details, other flyby missions are similar):

  1. _Flyby spacecraft launch:_ The flyby craft reaches Earth orbit as part of a "stack" consisting of (bottom to top) an Improved Saturn V, the flyby craft, and an Apollo Command and Service Module (CSM). The four-person flyby crew rides in the CSM during ascent to 185-kilometer-by-485-kilometer Earth orbit. The CSM/flyby craft combination detaches from the spent S-II stage, then the astronauts detach the CSM, turn it around, and dock with a temporary docking structure on the flyby craft's forward end. The crew then fires the CSM's engine to circularize the flyby craft's orbit at 485 kilometers. 

  2. _MS-IVB launch & assembly:_ Three Improved Saturn V launches 12 hours apart place three MS-IVBs into orbit. The rapid launch rate requires a new Saturn V launch pad at Kennedy Space Center - the only major new facility needed for the flyby program, the JAG estimates. The Improved Saturn V S-II stage injects the MS-IVB into 185-kilometer circular orbit, then a kick stage boosts it to 485-kilometer circular orbit. There the CSM/flyby craft combination performs a series of rendezvous and docking maneuvers to join the three MS-IVBs together end to end. The final assemblage consists of (fore to aft) the CSM/flyby craft and MS-IVB 1, MS-IVB 2, and MS-IVB 3. 

  3. _Earth-orbital launch:_ The flyby crew undocks the CSM from the docking structure and re-docks at the airlock port on the flyby craft's side. They transfer to the flyby craft, discard the CSM, and eject the docking structure. Launch from Earth orbit occurs between September 5 and October 3, 1975. Each MS-IVB fires its engine in turn, burns to propellant depletion, and detaches. As Earth and moon shrink into the distance the crew deploys the flyby craft's dish-shaped communications antenna and rectangular solar array. 

  4. _Flight to Mars_ lasts 130 days. During this time, the JAG report states, the astronauts are not idle - they perform a wide range of scientific experiments. These include solar studies; monitoring the biological effects of weightlessness; planetary and stellar observations; and radio astronomy far from terrestrial noise. 

  5. _Mars encounter_ takes place between January 23 and February 4, 1976. Several weeks before encounter the crew turns the astronomical telescope toward Mars. The pace quickens about 10 days before the craft reaches periapsis (point closest to the planet), when the craft is about 2 million kilometers from Mars. The astronauts use the probe deployment arm to unstow and release the probes. The flyby craft relays probe data to Earth at a high rate for several hours before and after periapsis passage. Flyby craft periapsis occurs 150-200 kilometers above the dawn terminator (line between night and day). During flyby the astronauts photograph Mars and its two moons, Phobos and Deimos. After the flyby craft leaves Mars' vicinity the probes beam their data directly to Earth at a reduced rate. 

  6. _MSSR rendezvous:_ MSSR lands on Mars a few hours before flyby craft periapsis passage and sets to work gathering rock and soil samples using scoop, brush, sticky tape, drill, and suction collection devices. Less than two hours after landing the ascent vehicle first stage ignites. If all goes well, the third stage delivers the samples to a point in space a few miles ahead of the flyby craft 16.5 minutes later, five minutes after flyby craft periapsis. 
    1. The crew retrieves the sample package using a boom-mounted docking ring and deposits it inside the EM biological lab. The report states that the ability to study a sample within minutes of its removal from Mars argues for the manned flyby concept - biological organisms in the sample could well perish during a long flight to a lab on Earth. 

    2. _Return to Earth_ requires 537 days. During this period the astronauts study the Mars samples and perform many of the same experiments performed during the Earth-Mars voyage. The flyby craft reaches the Asteroid Belt before falling back to Earth, making asteroid flybys a possibility. At aphelion the flyby craft is on the far side of the Sun from Earth, making possible simultaneous observations of both solar hemispheres. A few days before reaching Earth the crew enters the EEM and separates from the flyby craft, which flies past Earth into solar orbit. On July 18, 1977, the EEM slows down in Earth atmosphere, deploys parachutes, and lowers to a land landing. Just before touchdown solid rocket motors fire to cushion impact. Total flyby mission duration is 667 days.


	38. 1966:a plan for lunar exploration

The Lunar Exploration Working Group (LEWG) was one of five working groups NASA established in February 1966 "to examine the objectives and systems associated with a number of mission areas and document these findings in the form of a set of candidate program options covering the next 15 to 20 years." The LEWG and its companions (Earth Applications, Biosciences, Astronomy, and Planetary Exploration) were part of the on-going debate over NASA's post-Apollo future. This debate had begun almost as soon as President John Kennedy assigned the agency the goal of an American on the moon by the end of the 1960s (May 25, 1961). Resolving it became increasingly important as Apollo's culmination approached. Apollo 1, the first piloted test mission, was expected about three months after this report (February 1967), and the first lunar landing attempt was expected to follow about a year after that. Faced with a ballooning Federal budget deficit - largely the result of escalating U.S. military involvement in Indochina - President Lyndon Johnson's Bureau of the Budget projected little funding for post-Apollo lunar hardware before Fiscal Year 1973. Acknowledging this, the LEWG states that its report "represents neither policy nor firm intent." It quickly adds, however, that the document "illustrates the firm belief. . .that an effective lunar exploration plan can result from careful matching of scientific objectives with capabilities of unmanned systems and Apollo derivatives within a reasonable budget. . ." The LEWG describes a four-phase program spanning 1969-1980, which it says is "structured to permit uninterrupted exploration of the Moon in the post-Apollo period. . .[and] consistent with sound scientific rationale and fiscal responsibility."

  * _Phase I - Apollo, Block II/III Lunar Orbiters, and Block II Surveyors (1968-1975):_ NASA had logged two Surveyor soft lander missions (one of which, Surveyor 2, had failed) and one Lunar Orbiter mission by the time the LEWG completed its report. The agency planned five more Surveyors and four additional Lunar Orbiters before the first Apollo landing in 1968. These "Block I" automated missions were designed primarily to seek out potential landing sites in the "Apollo zone," the nearside equatorial region accessible to Apollo spacecraft. The years 1968-69 would see three Apollo landings. Two astronauts would spend 18-36 hours on the moon, venturing on foot no farther than one kilometer from their Lunar Module (LM), while a third astronaut orbited the moon in the Command and Service Module (CSM). Mission accomplished, the moonwalkers would lift off in their LM's ascent stage, rendezvous and dock with the CSM, and return to Earth. Advanced Lunar Orbiter and Surveyor missions would follow the Apollo flights. The LEWG proposes that five improved Block II Lunar Orbiters photograph the entire lunar surface between 1969 and 1971, and that ten Block II Surveyors land between 1970 and 1975, possibly at sites too remote and perilous for piloted landings. Block II Surveyors might carry automated rovers. Between 1972 and 1974, three Block III Lunar Orbiters would chart surface topography and composition, perhaps employing high-resolution film cameras. Exposed film might be recovered for return to Earth by astronauts in Apollo CSMs. The LEWG proposes that Lunar Orbiters serve also as radio relays for farside landers. 

  * _Phase II - Apollo Applications (1970-1973):_ NASA set up the Saturn-Apollo Applications (SAA) Office in August 1965. Within a year, SAA became known as the Apollo Applications Project (AAP). AAP was to include Earth-orbital space station missions and advanced lunar missions building on technology developed for the Apollo lunar landing program. The LEWG recommends one AAP lunar mission per year, each requiring two Saturn V launches. The first Saturn V of each mission would launch an LM Shelter and a CSM with two astronauts on board. LM Shelter would include supplies and exploration gear in place of ascent systems. Using controls aboard their CSM, the orbiting astronauts would remote-pilot the LM Shelter to a landing, then return to Earth. The second Saturn V would then place three astronauts, a CSM, and an LM Taxi on course for the moon. Two astronauts would land near the LM Shelter in the LM Taxi and make it their base camp for 14 days of exploration. They would drive up to eight kilometers from the landing site on a 1000-pound Local Scientific Survey Module (LSSM) rover. Mission accomplished, the astronauts would return to the LM Taxi, lift off in its ascent stage to rejoin their lonely colleague on the orbiting CSM, and blast for Earth.
  *     * _Phase III - Mobile Exploration (1974-76):_ The LEWG recommends three Phase III expeditions, each requiring one standard Saturn V and one uprated Saturn V. The uprated rocket - sometimes called a "188%" Saturn V - would place a new-design L-II landing stage with a camper-like MOBEX rover on top on course for the moon. The L-II's rocket motors would place MOBEX in lunar orbit, then fire again for descent and landing. After touchdown, the 9.9-ton rover would automatically unload from the L-II. The standard Saturn V would then launch three astronauts to lunar orbit. They would shut down their uprated CSM and descend in an uprated LM Taxi to land near MOBEX, which would trundle up to meet them under remote control from Earth. After mothballing their lander and checking out the rover, they would set out on a loop traverse. Possible routes include the 780-mile "Northwest Cloverleaf," which takes in the prominent craters Kepler and Aristarchus, and the 840-mile "East Loop," which includes Copernicus crater and the Carpathian Mountains. The LEWG envisions frequent stops lasting several days, during which the astronauts would drill for samples, set out instrument packages, and explore using an LSSM. Ninety days after landing, the astronauts would return to and reactivate their LM Taxi, lift off in its ascent stage, dock with and reactivate the orbiting CSM, and return to Earth.
    * _Phase IV - Temporary Station (1977-80):_ The final phase of the LEWG plan includes three missions over four years, each requiring three uprated Saturn V launches. The Apollo LM and CSM would be retired in favor of a Direct Ascent lander - that is, one which carries its crew directly to the moon and back. The first uprated Saturn V for each mission would launch a MOBEX and L-II landing stage to the moon. The second would launch an unpiloted, two-deck Lunar Laboratory Module (LLM). Delivering the heavy LLM to the moon would require an L-I course correction/lunar orbit insertion stage in addition to L-II. The third uprated Saturn V would launch the Direct Ascent lander with six astronauts on board. They would ride in a modified conical Apollo Command Module (CM) lacking a docking mechanism, but including expendables to support its occupants for seven days. In addition to the CM and L-I and L-II stages, the Direct Ascent lander would include an L-III stage for launching the CM back to Earth from the moon's surface. The LEWG's LLM habitat is based on a design for a Mars Mission Module, while the modified CM is based on an Earth-return vehicle for piloted Mars flyby missions. The L-I, L-II, and L-III stages would be similar, though L-II would have landing legs, and L-III would use storable propellants (L-I and L-II motors would burn liquid hydrogen and liquid oxygen). The LEWG hopes that sharing technology with the planetary program and using a common stage design will cut costs. The six astronauts would live in the Temporary Station for up to 180 days while taking their MOBEX on two or more long traverses. The LEWG then looks beyond Phase IV, noting that "the systems utilized during the temporary base phase will be suitable for later use in semi-permanent bases, if such facilities are desired for astronomical observation, lunar environment laboratories, [and] resource development or other utilization-exploitation activities."


	39. 1967:Voyager project summary

In 1960, the Jet Propulsion Laboratory (JPL) in Pasadena, California, commenced study of Voyager, a robotic spacecraft program for exploring Mars and Venus in the 1970s. NASA Headquarters formally approved Voyager in 1964. Cuts in NASA's space science budget, debate over how Voyager should be managed and launched, and new Mars atmosphere data from the Mariner 4 flyby (July 1965) delayed NASA's push for formal Voyager start-up until January 1967, when President Lyndon Johnson's Fiscal Year (FY) 1968 NASA budget called for $71.5 million for the new program. This 26-page booklet is not a planning document; rather, it exemplifies NASA's efforts to move Voyager beyond planning to development. It constitutes an introduction (and sales pitch) aimed at members of Congress and other individuals who would need to support Voyager for it to become part of NASA's 1970s plans. In his foreword, Homer Newell, NASA Associate Administrator for Space Science and Applications, explains that Voyager's chosen launch vehicle is the "awe-inspiring" Saturn V. One three-stage Saturn V rocket would launch two 12-ton Voyager spacecraft toward Mars. For comparison, Mariner 4, launched on an Atlas-Agena D rocket in November 1964, weighed only 574 pounds. Newell writes that

> [s]uccesses already achieved in the 1960s with unmanned spacecraft of limited weight and power. . .foretell the great work of exploration that lies ahead. . .With Voyager, the U.S. capability for planetary exploration will grow by several orders of magnitude. . .Voyager could well be the means by which man first learns of extraterrestrial life.

> NASA, the booklet explains, favors Mars over Venus as Voyager's first target because "the high surface temperatures on Venus make the existence of extraterrestrial life less likely than on Mars" and "the thin, normally transparent Martian atmosphere is conducive to detailed scanning of its surface features from orbit." In addition, "manned landings on Mars will someday be possible. . .[but] they may not be possible on Venus." This statement and others drew a link between Voyager and future piloted Mars voyages. The booklet places Voyager within an exploration program taking advantage of low-energy Mars launch opportunities that occur every 26 months.
> 
>   1. _Mariner 4 flyby (1964):_ Mariner 4 returned 21 close-up images of about one percent of Mars and measured atmospheric density. The booklet acknowledges that Mariner 4 atmosphere data forced a reassessment of the Voyager landing capsule design, which had assumed a martian atmosphere 10 percent as dense as Earth's. Mariner 4 found an atmosphere with 1 percent Earth density. The thin atmosphere forced reliance on heavy landing rockets in place of lightweight parachutes. According to NASA historians Edward Clinton Ezell and Linda Neumann Ezell, writing in their book _On Mars_(NASA SP-4212, 1984), the redesign bumped estimated Voyager cost beyond $1 billion. 
> 
>   2. _Mariner 1969 flyby:_ The spacecraft photographs the entire visible disk of Mars during approach and returns detailed images of 10 percent of the surface. 
> 
>   3. _Mariner 1971 flyby with atmosphere probe:_ The spacecraft drops a small sterilized probe into Mars' atmosphere to measure pressure, density, temperature, and composition as it plummets toward surface impact. The flyby spacecraft relays probe data to Earth and images 10 percent of Mars at high resolution. 
> 
>   4. _Voyager 1973 orbiters and landers:_ The 1973 Mars launch opportunity sees the first U.S. spacecraft in Mars orbit and the first U.S. Mars landing. The battery-powered lander searches for life and observes surface changes over the course of several days, while the solar-powered orbiter observes seasonal changes on a planet-wide scale. In this opportunity Voyager can land 860 pounds on Mars. 
> 
>   5. The _Voyager 1975 orbiters and landers_ use electric power from radioisotope thermoelectric generators. This allows the lander to survive for one martian year (two Earth years) - long enough to observe seasonal changes at its landing site. Voyager can land 1100 pounds on Mars in this opportunity. 
> 
>   6. The _Voyager 1977 and 1979 orbiters and landers_ see introduction of a lander-deployed Mars surface rover and biological experiments specially designed to study any life found by the 1973 and 1975 landers. In the 1977 and 1979 opportunities Voyager can land 1500 pounds on Mars.  
  

> 
> The 1973 Voyager Mars mission, which the booklet states is typical, occurs as follows:
> 
>   1. _Launch:_ Voyager launches from the Kennedy Space Center Complex 39 launch pads used for the Apollo Saturn V missions. The 1970s Mars launch windows last at least 25 days and include daily one-hour launch opportunities. Voyager Saturn Vs are identical to Apollo moon flights Saturn Vs - each consists of an S-IC first stage with five F-1 engines, an S-II second stage with five J-2 engines, and an S-IVB third stage with one J-2. The first stage burns for 2.5 minutes and falls away at an altitude of 39 miles, then the second stage burns for 6.5 minutes and falls away 114 miles high. The third stage then fires briefly to place itself, the twin Voyagers, and their protective streamlined launch shroud into Earth parking orbit. 
> 
>   2. _Interplanetary injection & Voyager spacecraft separation:_ Voyager's launch shroud is 22 feet in diameter and weighs 4.7 tons. In Earth orbit the shroud's forward portion ejects, exposing the forward Voyager to space. The S-IVB stage then ignites a second time to push the Voyagers out of Earth orbit toward Mars. After S-IVB shutdown, the forward Voyager separates. The shroud's cylindrical central portion then ejects to expose the aft Voyager, which separates from the S-IVB a short time later. In the 1973 opportunity each Voyager weighs 10.25 tons after separation. 
> 
>   3. _Interplanetary cruise:_ During the months-long cruise, the twin Voyagers turn their ring-shaped solar arrays toward the Sun. They use course-correction engines based on the Minuteman missile second-stage engine to place themselves on precise paths to Mars. The S-IVB trailing them makes no course adjustments, so misses Mars by a wide margin. Because the Voyagers perform course corrections at different times, they arrive at Mars up to 10 days apart. 
> 
>   4. _Mars orbit insertion:_ As each Voyager nears Mars, it fires its main rocket engine to slow down so Mars' gravity can capture it into an elliptical Mars orbit. Initial orbit low point is about 700 miles above Mars, while high point is beyond the orbit of Deimos, Mars' outermost moon (14,080 miles out). The booklet states that the leading Voyager main engine candidate is a modified Apollo Lunar Module descent engine. The complete Voyager propulsion system with propellants weighs 6.5 tons. Orbiter instruments turn toward Mars to examine proposed targets for the landing capsule. 
> 
>   5. _Capsule separation, de-orbit, descent, and landing:_ The 2.5-ton landing capsule ejects its sterilization canister, separates from the orbiter beyond Deimos, and fires a 415-pound solid-propellant deorbit rocket to slow down and fall toward the martian atmosphere. The deorbit rocket ejects, and the capsule enters at between two and three miles per second. Aerodynamic braking using the 20-foot-diameter conical heatshield cuts speed to between 400 and 1000 feet per second by the time the capsule falls to within 15,000 feet of the surface. The heatshield ejects, then the capsule fires its descent engines and deploys a supplemental parachute. During descent the capsule records TV images of the surface and studies the atmosphere. It releases the parachute, then slows to a hover ten feet above Mars. Its descent engines shut off and it drops to a gentle touchdown on three legs. 
> 
>   6. _Surface science:_ The 1973 capsule includes 300 pounds of science gear. Over several days the capsule searches for water and life, measures cosmic and solar radiation, and studies the atmosphere - for example, it measures windborne dust. 
> 
>   7. _Orbital science:_ The 1973 orbiter includes 400 pounds of science gear, which it uses to map the surface in detail, determine surface composition, search for surface changes, and measure solar and cosmic radiation. The orbiter also acts as a martian weather satellite. It uses its main engine to change orbit several times during its two-year operational life, allowing close study of much of the martian surface.


	40. 1967:lunar exploration summer studies

This conference built on the 1965 Falmouth Conference to help define lunar landing sites for Apollo missions. Participants included geologist-astronaut Harrison Schmitt and U.S. Geological Survey geologists Michael Duke, Harold Masursky, and Eugene Shoemaker. They divide the Apollo program into three "Early Apollo" (EA) and nine Apollo Applications Program (AAP) expeditions. Tentative EA sites are Sinus Medii, Mare Fecunditatis, and Flamsteed crater. Two of the AAP sites are manned lunar orbiter flights and seven are lunar surface expeditions. According to the proceedings

> the most important need [for AAP surface missions] is for increased operating range on the Moon. On the early Apollo missions it is expected that an astronaut will have an operating radius on foot of approximately 500 meters [1640 feet]. It is imperative that this radius be increased to more than 10 kilometers [6 miles] as soon as possible.

To increase operating range, AAP expeditions include one-man Lunar Flying Units (LFUs) and two-man Local Scientific Survey Module (LSSM) rovers with ranges of 20 and 50 kilometers, respectively. LSSMs operate as automated rovers when astronauts are not present. AAP missions occur as follows:

  * _AAP Mission 1:_ Manned lunar orbiter performs detailed mapping photography and geochemical remote sensing. 

  * _AAP Mission 2_ sees two astronauts landing an Extended Lunar Module (ELM) with two LFUs near the central peaks of 50-mile-wide Copernicus crater. The surface stay lasts 72 hours and includes four LFU flights, two of which reach the summits of the Copernicus peaks. 

  * _AAP Mission 3:_ Davy Rille - similar to the AAP-2. 

  * _AAP Mission 4:_ Copernicus rim - similar to AAP-2 and AAP-3. 

  * _AAP Mission 5_ sees two astronauts landing an ELM with two LFUs in the Marius Hills near a pre-landed Lunar Module (LM) truck, an automated one-way cargo lander based on the LM. The LM truck carries the first LSSM. This expedition requires two Saturn V launches - one for a piloted Apollo CM and LM truck, and one for a piloted CM and piloted ELM. After the crew departs, the LSSM sets out unmanned to Aristarchus crater, collecting samples along the way. 

  * _AAP Mission 6:_ Cobra Head, near Aristarchus - similar to AAP-5. The astronauts retrieve samples collected by the LSSM arrived from the Marius Hills, then use a new LSSM to perform three traverses. They also perform five LFU sorties. After the crew departs their LSSM sets out across Mare Imbrium toward Hadley Rille. 

  * _AAP Mission 7:_ Manned lunar orbiter - similar to AAP-1. 

  * _AAP Mission 8:_ includes a 7-to-8-day stay at Alphonsus crater, a Lunar Payload Module (LPM) or Augmented LPM advanced LM-based cargo lander, and eight LFU and five LSSM traverses. After the astronauts leave, their LSSM sets out across the Lunar Highlands toward Sabine and Ritter craters. 

  * _AAP Mission 9:_ Sabine and Ritter - similar to AAP-5 and 6 but lacks an LSSM. The astronauts pick up samples collected by the AAP-8 LSSM.

The scientists meeting at Santa Cruz also propose AAP expeditions to the moon's poles, Tycho crater, Mare Orientale, and Hadley Rille, but state that sending expeditions to these sites will require further study.


	41. 1967:manned planetary flyby studies

NASA's Marshall Space Flight Center commissioned the Early Manned Planetary Interplanetary Roundtrip Expeditions (EMPIRE) studies in 1962. EMPIRE was the first in a series of NASA studies of piloted planetary flyby missions. Even as the EMPIRE contractors completed their flyby studies, however, the Mariner 2 probe undermined the piloted flyby concept by performing the first automated flyby exploration of Venus (December 1962). Mariner 4 performed a similar feat at Mars in June 1967. Despite doubts at high levels about the desirability of piloted flybys ,the NASA Headquarters-led Planetary Joint Action Group (JAG) commenced planning for a 1975 piloted flyby mission as a "new start" in the Fiscal Year (FY) 1969 NASA budget. The JAG had some reason to be hopeful that its flyby mission might be funded. In January 1967, President Lyndon Johnson had requested a $5.1-billion FY 1968 NASA budget, a modest increase over FY 1967. In this report, a follow-on to the October 1966 JAG "Phase 1" study,the NASA Manned Spacecraft Center (MSC) in Houston proposes a 90-ton, 21.6-foot-diameter flyby spacecraft with four modules. They are (aft to fore in flight/bottom to top on the launch pad):

  * The 18.8-foot-long _Experiment Module (EM)_ varies according to mission, but always the primary payload is an automated probe suite including at least one large Mars Surface Sample Return (MSSR) lander. The probes are released beginning 15 days before planet flyby. The MSSRs land, grab samples, and lift off to rendezvous with the flyby spacecraft as it passes Mars. Before launch from Earth the probes are sealed in the EM and sterilized to avoid biological contamination of their targets. In previous manned flyby studies the presence of astronauts was justified in part by their ability to service the probes during flight, but that is not possible here because servicing would introduce contamination. The EM includes an external remote sensor pod and an airlock for spacewalks. An aerodynamic shroud covers the pod during flight through Earth's atmosphere. Twin solar arrays and dish antennas stow between the EM and the Saturn V launch vehicle; they deploy after the flyby spacecraft leaves Earth orbit and separates from its Earth-departure propulsion stage. 

  * _Mission Module (MM)_ \- The MM is the crew's main living and working space. The basic four-man MM is 11 feet long with a central cylinder containing the command and experiment control stations, space suit storage, and ceiling hatch to the EEM. The surrounding toroidal volume includes four private compartments, galley, wardroom, hygiene area, and floor-mounted EVA airlock access hatch. Volume is 2240 cubic feet. The report also describes 6- and 8-man MMs. 

  * _Earth Entry Module (EEM)_ \- A modified Apollo Command Module (CM) The four-man EEM serves triple duty as abort vehicle, solar flare radiation shelter, and end-of-mission Earth reentry vehicle. CM modifications to create the EEM include an enhanced heat shield permitting higher atmosphere entry velocities; nose docking unit and tunnel removed to make more room for parachutes (possibly including a steerable paraglider); solid-fueled landing rockets; stowable net couches; and a hatch through the heat shield leading into the MM. On the launch pad the EEM's nose points upward. The study also considers 6- and 8-man EEMs. 

  * The _Midcourse Propulsion Module (MPM)_ at the front of the flyby spacecraft performs course corrections during a normal mission and crew abort if the Earth-departure stages fail. In an abort, the MPM and EEM separate, then the MPM fires its two rocket engines for emergency Earth return. The MPM has four oxidizer tanks and two fuel tanks. On the launch pad its engine bells point upward and are covered by a streamlined shroud. The EEM nests among the MPM's propellant tanks for additional radiation shielding. During return to Earth, the crew enters the EEM and discards the MPM, freeing the EEM to maneuver for atmosphere entry. 

The flyby craft reaches Earth orbit on a two-stage Saturn V rocket. Assembly can occur in either circular Earth orbit or elliptical Earth orbit. For circular orbit assembly, the crew reaches the flyby spacecraft in an Apollo Command and Service Module (CSM)-based logistics craft on top of the flyby craft. In orbit the CSM docks with the flyby craft for crew transfer then is discarded. The astronauts ride in the CSM during launch rather than in the flyby craft so they can use the CSM launch escape system if the Saturn V rocket fails. After the crew boards the flyby craft, more two-stage Saturn Vs lift off. Each carries an Earth-departure stage of a design based on the Saturn V S-IVB third stage. For elliptical orbit assembly the crew reaches the flyby craft in a CSM vehicle launched on top of one of the Earth-departure stages. The first Earth-departure stage docks with the aft (EM) end of the flyby craft; the second docks with the aft end of the first; and so on. The number of stages required depends on the energy needed to perform a mission in a given launch opportunity. The 1975 Mars opportunity, for example, needs two stages. The size and weight of the stages is not specified; however, in illustrations it appears longer than the MS-IVB stage invoked in the 1966 Planetary JAG report. After checkout the flyby spacecraft departs Earth orbit.

The report presents the following mission profiles:

  * _1975 Mars Twilight Encounter_ \- The flyby spacecraft passes Mars on the outbound leg and releases six probes, including a 12,538-pound MSSR. The flyby craft reaches aphelion (farthest point from the Sun) in the asteroid belt, where it points the empty experiment compartment forward to serve as a meteoroid shield. Remote sensors for this mission include a 40-inch telescope and multispectral and wide-angle cameras. 

  * _1977 Triple Planet Encounter_ \- The spacecraft drops inside Earth's orbit and flies past Venus, where it releases 16 probes, including four meteorological balloons and two landers. At Mars the spacecraft releases two 7000-pound MSSRs. During return to Earth the spacecraft again flies past Venus, this time releasing ten probes. Remote sensors for Mars and Venus include those for the 1975 mission plus radar and passive microwave imagers for Venus studies. 

  * _1978 Double Planet Encounter_ \- The spacecraft drops inside Earth's orbit to fly past Venus, where it releases five probes. At Mars the spacecraft releases nine probes, including three 7000-pound MSSRs. Remote sensors are identical to the ones carried on the 1977 mission.


	42. 1967:an extended lunar mission

The 100-kilometer-wide "Flamsteed Ring" (Flamsteed P) lies in the moon's Oceanus Procellarum (Ocean of Storms) east of the dark-floored crater Grimaldi and south-west of the bright ray crater Kepler. Surveyor 1 landed there on June 2, 1966. Today, the Ring is widely accepted to be an ancient impact crater flooded by lava from the formation of Oceanus Procellarum. In 1967, however, a considerable body of opinion held that it formed as lava squeezed toward the surface some time after Oceanus Procellarum formed. The possibility that it might point to recent lunar volcanism made the Flamsteed Ring a candidate Apollo Lunar Module (LM) landing site. Scientist Noel Hinners points out another of the Ring's attractions - Lunar Orbiter 1, which reached lunar orbit on August 14, 1966, imaged the area to a resolution of only one meter. He writes that his plan for a baseline Extended LM (ELM) mission "profited immensely from the availability of high resolution orbital photography," and adds that "such photography will be required for all realistic future mission planning and thus for all potential lunar landing sites." His ELM mission draws on recommendations made by the Apollo Applications Project (AAP) Lunar Missions Ad Hoc Study Team. The baseline LM can stay on the moon for 36 hours; ELM uses a solar panel and extra consumables to double staytime. ELM can transport 1000 pounds of exploration gear to the Flamsteed Ring, include two 150-pound Lunar Flying Unit (LFU) rocket flyers and two spare space suit backpacks. The astronauts draw upon the 500 to 1000 pounds of propellants left over in the ELM descent stage after touchdown to fuel the LFUs, and save time by changing their exhausted backpacks outside the ELM between moonwalks. The ELM is capable of precision landing within 100 meters of a target, permitting detailed pre-flight traverse route planning. The Flamsteed Ring mission includes six moonwalks (two per day):

  1. _First moonwalk - inspect LM:_ The two astronauts ("A" and "B" - presumably Commander and Lunar Module Pilot, respectively) deploy the ELM's solar panel on the surface and conduct a short geological traverse on foot through a nearby boulder field. Hinners calls ability to communicate out of view of the LM "[o]ne of the unknowns of lunar surface exploration," and proposes that "such be attempted in a series of tests whereby one astronaut slowly proceeds out of line-of-sight either walking behind hills or boulders or by entering shallow craters." 

  2. _Second moonwalk - ridge-mare traverse:_ The astronauts walk to a place where the Flamsteed Ring ridge meets the basalt mare material making up Oceanus Procellarum. They collect samples so Earth geologists can date ridge and mare, then carefully monitor their exertions as they climb the ridge. They then collect samples from an impact crater on the ridge one kilometer from the ELM. 

  3. _Third moonwalk - LFU orientation and ALSEP experiment package deployment:_ The astronauts load the LFUs with surplus ELM propellants and practice flying them. Hinners writes that the LFUs "are new exploration tools," so require "an extensive check-out period with many stops and a lot of hovering close to the ELM. . ." Check-out covers 10 kilometers and uses 400 pounds of propellants. He adds that "there will be extreme conservatism exercised in both distance covered and velocity utilized on early [LFU] missions. . .any time one astronaut is using an LFU, the other remains near the ELM with a second LFU available for rescue." Hinners notes, however, that an LFU weighing only 150 pounds might be unable to carry two astronauts. Following check-out, astronaut A flies to the planned ALSEP deployment site. He carefully selects a deployment location while astronaut B carries ALSEP to the site on foot. 

  4. _Fourth moonwalk - LFU ridge traverse:_ Astronaut A uses 125 pounds of propellants to fly the LFU a total of six kilometers. Loading a core drill onto the LFU, he flies first to the ridge crest, then to a place where ridge meets mare, then to an "enigmatic. . .rock moraine," and finally to an "eroded" crater. At each stop he collects a core sample. Astronaut B, meanwhile, performs "detailed observations" and "sample preparation" while standing by the second LFU. 

  5. _Fifth moonwalk - LFU mare traverse:_ Astronaut B uses 105 pounds of propellants to fly the LFU a total of 5.5 kilometers. He collects core samples in an "older" mare area, then at a "crater with slump material," and finally in an area of "patterned mare." Astronaut A, meanwhile, adjusts the ALSEP as necessary while standing by the second LFU. 

  6. _Sixth moonwalk:_ The final moonwalk ties up loose ends. The astronauts hike to a new area or re-visit a site. They then prepare samples gathered during their six moonwalks for return to Earth.


	43. 1967:an advanced manned planetary flyby

On August 3, 1967, NASA's Manned Spacecraft Center in Houston distributed a Request for Proposal (RFP) to 28 companies asking them to describe how they would perform a design study for a piloted encounter/retrieval spacecraft. The term "encounter/retrieval" replaced the term "flyby" because the latter had become associated with robotic flyby missions, and because of high-level doubts about the piloted flyby concept ([see](https://web.archive.org/web/20010815182843/http://members.aol.com/dsportree/ex67aba.htm)). The RFP asked the companies to describe how they would accomplish five tasks.

  * _Task 1 - Mission Module (MM) Design:_ The MM would provide the encounter/retrieval crew with living and working space during the mission. MSC asked that the companies also consider whether the MM design could serve as a six-to-12-man Earth-orbital space station. 

  * _Task 2 - Earth Entry Module (EEM) Design:_ The EEM would detach from the encounter/retrieval spacecraft as it flew past Earth at mission's end, reenter Earth's atmosphere, and land. The EEM would be derived from the three-person Apollo Command Module (CM) design but would carry up to six people. 

  * _Task 3 - Propulsion Module (PM) Design:_ The PM would perform course corrections during the encounter/retrieval mission. In addition, the PM and EEM would return the crew safely to Earth if the encounter/retrieval spacecraft malfunctioned during or immediately following launch from Earth orbit. 

  * _Task 4 - Experiment Module (EM) Design:_ The EM would carry scientific probes and instruments, including at least one Mars Surface Sample Retrieval (MSSR) lander. The MSSR would land on Mars, pick up samples, and launch the samples back to a biology lab in the EM. 

  * _Task 5 - Spacecraft Integration:_ This catch-all task required, among other things, that the company describe how the four modules would come together to form the encounter/retrieval spacecraft and how the combined spacecraft would operate.

The RFP's task list assumed a basic spacecraft configuration very similar to the flyby spacecraft design studied by the NASA Planetary Joint Action Group (JAG) ([see](https://web.archive.org/web/20010815182843/http://members.aol.com/dsportree/ex66e.htm)). In its response, the Douglas Aircraft Company, prime contractor for the Mercury and Gemini capsules and the S-IVB stage (the Saturn V third stage), offers the following "illustrative spacecraft design":

  * _Task 1:_ Douglas finds that a four-person crew is adequate for the encounter/retrieval mission. The basic MM structure is a 7.65-ton, 21.67-foot-diameter "pressurized canister." Douglas finds that the MM planetary and space station requirements are different, and states that "[i]t is not immediately clear, therefore, how considerations for dual usage. . .will affect the basic design, or whether it is practical at all." In general, making the MM suitable for both adds weight to the planetary MM. The planetary MM has two decks, each seven feet high, that can be sealed off from each other. For redundancy each deck includes all vital subsystems, a two-man console for controlling the spacecraft, and a "more or less conventional space toilet with forced air flush and water-jet wash." Subsystems are contained beneath the deck floors. Each crewmember has a "semi-private" stateroom with bed, desk, and removable privacy partition. Food and waste containers stored behind the bed provide added radiation and meteoroid protection while the astronaut is in his stateroom (40 percent of the time, Douglas estimates). The MM carries twin solar arrays on booms that provide electricity to the entire encounter/retrieval spacecraft. A unique feature of the MM is a fiber optics lighting system which "pipes" sunlight into the MM to minimize electricity use. 

  * _Task 2:_ Douglas proposes two possible Apollo CM-based EEM designs, designated "preliminary" and "baseline." The former receives the most attention. The preliminary EEM includes a cylindrical docking tunnel on its nose. It weighs 6.5 tons and measures 163 inches in diameter (9 inches wider than the Apollo CM). This boosts the EEM's internal volume from the CM's 356 cubic feet to 404 cubic feet, allowing it to hold the six people required by MSC's RFP. Douglas finds that the volume around the preliminary EEM's docking passage is too small to hold steerable land landing parachutes. The baseline EEM is also 163 inches across, but has a hatch through its heatshield for entrance into the MM. It has no docking system, leaving adequate room in its nose for steerable parachutes. Tricycle land landing skids deploy through the heatshield. The company notes that "[a]cceptance of the water landing. . .would significantly relieve the design requirements." Fuel cells in the EEM draw hydrogen and oxygen from the PM to generate electricity for the two modules when they are not attached to the encounter/retrieval spacecraft (during orbital assembly and Earth approach). Batteries provide electricity when the EEM is separated from the PM (during Earth atmosphere reentry and landing). 

  * _Task 3:_ The PM weighs 3.3 tons empty. Together the PM and preliminary EEM resemble an oversized Gemini capsule. The PM carries 15 tons of liquid hydrogen fuel and liquid oxygen oxidizer in four tanks for its twin RL-10 rocket engines and the encounter/retrieval spacecraft's main attitude control system. Douglas provides the following breakdown of propellant use during a typical mission: 

    * _Boil off:_ 12 percent
    * _Assembly maneuvers in Earth orbit:_ 5 percent
    * _Attitude control:_ 2 percent
    * _Course corrections:_ 30 percent
    * _Reserve:_ 51 percent

The PM carries enough reserve hydrogen and oxygen for the EEM's fuel cells to provide up to 18,000 kilowatt-hours of electricity to the MM in the event of solar panel failure. The reserve can also be used to provide up to 6.25 tons of breathing oxygen or up to 7.5 tons of water to the MM if the life support system fails.

  * _Task 4:_ The Douglas EM weighs 3.25 tons. It consists of the Onboard Experiment Canister (OEC) and the Probe Canister. The OEC has two compartments connected by an airlock. The smaller compartment, normally kept unpressurized, contains the spacecraft's telescope, two docking units for MSSR sample-return capsules, and bioisolation chambers for sample handling. It can be pressurized for shirt-sleeve access by the astronauts. The larger, permanently pressurized compartment serves as experiment and film laboratory, and includes the heavily shielded film vault and windows for photographic instruments. The Probe Canister, which varies in volume between 5000 and 10,000 cubic feet depending on the type and number of probes carried, is equipped with a "swing-tail door" or side door for releasing automated probes during approach to the target planet. The probes are packed inside individual sterilized containers. Each container includes built-in glovebox-type gloves that allow the astronauts to reach inside and service the probe without introducing biological contamination. 

  * _Task 5:_ The integrated four-module encounter/retrieval spacecraft and its propellants weigh 38.15 tons regardless of mission. For most missions total spacecraft weight comes to about 100 tons. The remaining 61.85 tons is apportioned among experiments and probes, meteoroid and radiation shielding, life support consumables, and spare parts according to mission. The 1977 Mars Encounter mission, for example, explores one planet using about 35.4 tons of experiments and probes; the 1978 Dual-Planet Encounter explores two planets (Mars and Venus), so includes about 47.3 tons of experiments and probes. Because it passes through the Asteroid Belt, the 1977 mission includes about 17 tons of meteoroid shielding; the 1978 mission, by contrast, achieves the same level of astronaut safety with 4.15 tons. The 1978 mission needs 1.55 tons of radiation shielding; the 1977 missions relies on its great bulk of meteoroid shielding to block radiation. The 1978 mission lasts 658 days, so includes 6.65 tons of life support consumables and 2.2 tons of spares; the 1977 mission is longer (700 days), so needs about 7 tons of consumables and 2.35 tons of spares. Total pressurized living space in the MM and EM amounts to 3000 cubic feet. The Douglas encounter/retrieval mission plan closely follows the Planetary JAG flyby plan. The summary below largely emphasizes the Douglas plan's unique features. 

    1. _Launch from Earth and orbital assembly:_ The encounter/retrieval spacecraft reaches circular assembly orbit on a two-stage Saturn V rocket. The EEM sits on top of the PM, which in turn sits on the EM. The MM, at the bottom of the stack, rests on the Saturn V second stage. The EEM and PM detach and fly around the EM and MM. The astronauts perform a visual inspection of the MM and EM, then dock with and enter the MM. They conduct a 10-day Earth-orbital shakedown, then use the PM to rendezvous and dock with the first Orbital Launch Vehicle (OLV). Douglas bases the OLV on its S-IVB stage (the Saturn V third stage used in Apollo moon missions). Each OLV reaches Earth orbit on a two-stage Saturn V. The company also describes an elliptical-orbit assembly method based on a BellComm study ([see](https://web.archive.org/web/20010815182843/http://members.aol.com/dsfportree/ex67ac.htm)). Orbital assembly requires five days. 

    2. _Launch from assembly orbit:_ Launch countdown begins about four hours before first OLV ignition. The OLVs ignite in succession, exhaust their propellants, and detach. In the Planetary JAG plan the astronauts ride in the EEM during Earth-orbit departure to allow rapid escape back to Earth in case the flyby spacecraft fails. Douglas finds that fast escape is unnecessary; abort to Earth using the EEM and PM remains possible for "more than an hour" after the last OLV shuts down, giving the astronauts time to move to the EEM if a critical failure occurs. In an abort the PM's engines slow the EEM, placing it on a 36-hour trajectory back to Earth. The MM's large display panels allow the astronauts to monitor their spacecraft's condition in more detail than would be possible using the small panels on the EEM. 

    3. _Outbound transplanetary cruise:_ For a Mars Encounter mission launched in October 1977, this leg of the journey lasts 155 days; for a Dual-Planet mission launched in December 1978, the spacecraft flies to Venus in 147 days. Crew workload is light (15 to 20 man-hours per day) during most of the outbound flight. One crewmember is on duty at a control console at all times. The astronauts perform several course corrections using the PM. During off-duty hours, crewmembers use display screens and keyboards on the spare control console to view movies and books, play chess with an opponent on Earth, or write letters home. Inflight experiments include solar observations, micrometeoroid collection, planet and asteroid photography, analysis of interplanetary gas composition, biomedical crew monitoring, and engineering experiments such as using lasers for interplanetary communication. 

    4. _Planet approach and encounter:_ About two weeks before planetary encounter the crew checks out the EM's cargo of probes for the first time since leaving Earth. About 10 days from encounter the astronauts begin probe deployment. The last chance to survey the planet with remote sensors, analyze the data, and apply that analysis to planning the experiment program at closest encounter occurs a week before encounter. At that time the smallest object visible on the target planet is two miles across. Douglas notes that this resolution "is sufficient to identify gross topographic features such as highlands, plains, large valleys, and mountains, though unfortunately, it is not adequate to identify areas of plant life." All four astronauts can work 24 hours straight on the day of closest encounter. One astronaut maintains communication with Earth, orients the spacecraft, and monitors vital systems; one operates the telescope/camera used for mapping; another controls the other sensors; and the fourth operates the probes. For missions including a Mars encounter, the spacecraft collects the sample containers from the MSSR probes soon after closest encounter; sample analysis begins immediately "to minimize the effect of space radiation and null-gravity." Other encounter experiments include planetary radiation belts measurement, planetary cloud viewing, and atmospheric composition measurement. 

    5. The _inbound transplanetary cruise_ is busier for the crew than the outbound cruise. It begins with 10 days of post-encounter data processing, analysis, and transmission. In addition to data collected during the planetary encounter, the astronauts transmit to Earth their suggestions for improvements in the encounter/retrieval spacecraft design. These are applied to the next encounter/retrieval mission spacecraft, which is under construction on Earth at this time. Subsystems begin wearing out during this leg of the voyage, so must be serviced or replaced more frequently. Trajectory corrections must be made with great care during the flight back to Earth to ensure that the EEM will hit the planned Earth landing (or splashdown) area. For the 1977 Mars Encounter, this leg of the journey lasts 545 days. The 1978 Dual-Planet mission follows its Venus encounter with a 394-day cruise to Mars and a 117-day inbound cruise to Earth. 

    6. _Approach to Earth, entry, landing:_ At least a month before Earth return the astronauts prepare their bodies for reentry deceleration by increasing their exercise regimen. They also begin reacquainting themselves with EEM entry and landing procedures. To help the EEM achieve the trajectory accuracy needed to reach its Earth landing target, Douglas proposes an aerodynamic-capture maneuver in which the EEM enters Earth's atmosphere, uses drag to slow down, enters Earth orbit, then reenters and lands.


	44. 1968:an integrated manned interplanetary spaceship

The interplanetary vehicle design developed by Boeing for NASA's Langley Research Center powerfully influenced Mars mission planning in the 1968-71 period. If the momentum built up during Apollo had not been halted, Mars expeditions might have flown in the 1980s using vehicles based on this Boeing concept. The 582-foot-long Mars ship consists of a 108-foot-long piloted spacecraft and a 474-foot-long "space acceleration system" made up of five nearly identical Primary Propulsion Modules (PPMs) arrayed in three Propulsion Modules (PMs). Fore to aft, the piloted spacecraft consists of

  * automated probe compartment 

  * Mars Excursion Module (MEM) piloted lander - The MEM adopted by Boeing, a conical two-stage vehicle, is based on a 1968 North American Rockwell design. 

  * "Interstage compartment" with docking ports for Apollo Command Module (CM)-based logistics vehicles, remote sensing apparatus, and additional automated probes 

  * Mission Module (MM) with four decks, arranged as follows (fore to aft) - 

    * _Deck One_: crew quarters (6 staterooms); two waste management compartments; shower compartment; medical compartment 

    * _Deck Two_: recreation/conference room/spares storage; command center; food storage and preparation; water management 

    * _Deck Three_: food, water, and spares storage; environmental control; radiation shelter/emergency pressure compartment with emergency spacecraft controls 

    * _Deck Four_: labs for electronics, bioscience, geophysics, and optics; science information center

  * Earth Entry Module (EEM) with ablative heat shield, parachutes, and flotation bags for water landing.

The five PPMs in the space acceleration system are each 33 feet in diameter, 158 feet long, and hold 385,000 pounds of liquid hydrogen propellant at Earth-orbit launch. The aft 40 feet of each PPM is a 195,000-pound thrust NERVA nuclear rocket engine with an engine bell 13.5 feet in diameter. The spacecraft is assembled through ten launches of the Saturn IB rocket and a Saturn V-derived vehicle called the Saturn V-25 (S)U. The 470-foot-tall Saturn V-25 (S)U launch vehicle consists of a two-stage liquid oxygen/liquid hydrogen core (MS-IC and MS-II stages) with up to four 156-inch-diameter strap-on solid-fueled rocket motors. The Saturn V-25 (S)U with four strap-ons is capable of delivering 548,400 pounds to a 262-mile circular Earth orbit. Apollo Saturn V launch pads 39-A and 39-B at Kennedy Space Center (KSC) are modified to launch the Saturn V-25 (S)U, and a new Pad 39-C built north of the existing pads. Other KSC changes include a solid rocket motor processing building and Vehicle Assembly Building hi-bay modifications. Mars ship launch and assembly occurs as follows:

  * _Launch 1_: Saturn V-25 (S)U core (no strap-ons) places the piloted Mars spacecraft (MEM, MM, EEM) into 262-nautical-mile assembly orbit. 

  * _Launch 2_: Saturn IB places into orbit a modified Apollo CM carrying a six-man assembly & test crew. CM docks with Mars spacecraft. 

  * _Launch 3_: Saturn V-25 (S)U with four strap-ons places the first PPM of the space acceleration system into assembly orbit. The module docks to the aft end of Mars spacecraft. 

  * _Launch 4_: Saturn V-25 (S)U with four strap-ons places a second PPM into assembly orbit. The second PPM docks to the aft end of the first. 

  * _Launch 5_: Reserved for crew or parts transport as necessary. 

  * _Launch 6_: Saturn V-25 (S)U with four strap-ons places the third PPM into assembly orbit. It docks with the aft end of the second PPM. 

  * _Launch 7_: Saturn V-25 (S)U with four strap-ons places the fourth PPM into assembly orbit. The fourth PPM docks backwards to the aft end of the third PPM, then pivots into position on the third PPM's starboard side. 

  * _Launch 8_: Saturn V-25 (S)U with four strap-ons places the fifth and final PPM into assembly orbit. The fifth PPM docks backwards to the third PPM, then pivots into position on the third PPM's port side 1. 

  * _Launch 9_: Reserved for crew or parts transport as necessary. 

  * _Launch 10_: Saturn IB places into assembly orbit a modified Apollo CM carrying the six-person Mars expedition crew. Mars expedition crew replaces assembly & test crew. Expedition crew CM is cast off prior to orbital departure.

The first PPM and second PPMs constitute Propulsion Module-3 (PM-3) and PM-2, respectively; the third, fourth, and fifth PPMs constitute PM-1. Some of the proposed Mars expedition profiles include an inbound or outbound Venus flyby, during which the crew releases automated probes to explore the planet. The study lists opportunities for nine Venus-swingby, one conjunction-class, and five opposition-class Mars expeditions between November 1978 to January 1998. The conjunction-class mission lasts 900 days, while the Venus-swingby and opposition-class missions last from 460 to 680 days. The basic mission sequence is as follows:

  * PM-1 ignites its three NERVA engines and burns until it depletes its liquid hydrogen propellant, placing the vehicle on course to Mars. PM-1 discarded. 

  * Course correction burns use Outbound Midcourse Correction System chemical rockets on PM-2. 

  * PM-2 ignites its NERVA engine and burns until it depletes its propellant, placing the vehicle in high Mars orbit. PM-2 discarded. 

  * Orbit trim burn using Orbit Trim System chemical rockets on PM-3 places vehicle in 540-nautical-mile Mars operational orbit. 

  * MEM and automated probes released; after the MEM separates its 4200-pound deorbit motor fires, then jettisons. Upon completing Mars atmosphere entry, the MEM heatshield ejects, exposing folded landing gear and a descent engine fueled by liquid oxygen-liquid methane propellants. The landing gear unfolds. 

  * MEM landing and surface stay; three astronauts explore for 30 days. At the end of their stay the astronauts load up to 900 pounds of samples into the ascent stage and lift off. 

  * MEM ascent and docking; the ascent stage engine is fueled by eight conical strap-on tanks. Once empty, the tanks fall away and the ascent stage continues into orbit drawing on two internal propellant tanks. The MEM ascent stage docks with the orbiting spacecraft, and the three surface explorers rejoin their colleagues in the MM. MEM ascent stage jettisoned. 

  * PM-3 ignites its NERVA engine and burns until it depletes its liquid hydrogen propellant, placing the vehicle on course for Earth. PM-3 discarded. 

  * Course correction burns occur using chemical propulsion Inbound Midcourse Correction System. Some mission profiles include an inbound Venus flyby. 

  * EEM separates from Mars ship; Inbound Midcourse Correction System steers empty ship away from Earth collision, into solar orbit. 

  * EEM enters Earth's atmosphere; parachute descent and splashdown.


End file.
